This paper summarizes the policy evolution of sustainable development of resource-based cities (RBCs) in China over the past 20 years and analyzes the results of promoting sustainable development of RBCs. The main points of this paper are as follows: (1) The evolution path of sustainable development policy of RBCs in China in the study period basically follows the development logic of combining problem orientation and goal orientation, experiencing from "administrative intervention", "administrative guidance" to "comprehensive governance" changes. Generally speaking, the policy evolution can be roughly divided into three stages, namely, the stage of resolving difficulties, the stage of comprehensive promotion and the stage of high-quality development. (2) At present, China has formed a "four-in-one" policy framework for sustainable development of RBCs, which includes the transformation of resource-exhausted cities, innovative development of resource-rich cities, transformation and upgrading of independent industrial and mining areas, and comprehensive treatment of coal mining subsidence areas. (3) RBCs make full use of local advantages, and initially form some characteristic transformation development models. (4) In the New Era, RBCs are faced with severe challenges such as large carbon emission reduction tasks, weak economic growth, and bottlenecks hindering balanced and high-quality development in special areas. It is urgent to make all-out efforts to solve key problems and promote sustaibable development.

As a new mode of transportation in modern society, high-speed railway is an important external driving force for the economic transformation of resource-based cities. Based on the panel data of 114 resource-based cities in China from 2004 to 2018, this paper analyzes the impact of the opening of high-speed rail on the economic transformation of resource-based cities in China by adopting the multi-period differential difference method. The results show that: In general, the opening of high-speed railway plays a significant role in promoting the industrial structure transformation and economic growth of resource-based cities. The opening of high-speed rail also has a heterogeneous effect on the economic transformation of resource-based cities in different development periods: The opening of high-speed railway has a significant promotion effect on the optimization of the industrial structure of coastal resource-based cities, but its impact on economic growth is insignificant. In contrast, the optimization of industrial structure of resource-based cities in inland areas is not significantly affected by the opening of high-speed railway, and its economic growth is significantly affected by high-speed railway. The opening of high-speed rail also has heterogeneous impacts on resource-based cities with different development periods: The opening of high-speed railway has a significant promoting effect on the optimization of industrial structure in the growing and regenerating resource-based cities, but its effect on industrial structure optimization of mature and declining resource cities is not obvious. By contrast, the opening of high-speed railway has no obvious influence on the economic growth of the growing and regenerating and mature resource-based cities, but has a significant promotion on the economic growth of the declining resource-based cities.

Industrial transformation is an important development problem faced by resource- exhausted cities, and exploring the evolutionary mechanisms of industrial transformation and its economic resilience in resources-exhausted cities is of great significance to realize high-quality urban development. From the perspective of evolutionary economic resilience, taking Daye city of Hubei province as an example, this paper constructed an evaluation index system of economic resilience in resource-exhausted cities, and the entropy value method and partial least squares (PLS) are adopted to quantitatively reveal the evolutionary characteristics and driving mechanisms of economic resilience during the industrial transformation of Daye city from 2000 to 2019. The results showed that: (1) The economic resilience of the study area had undergone the evolutionary stages of recession adaptation, resistance to recovery, and response improvement, which corresponded to the study area's economic recession transition period (2000-2009), development recovery period (2010-2014), and efficient improvement period (2015-2019), and the level of economic resilience showed a "slow to fast" rising trend. (2) From 2000 to 2019, the driving factors of the evolution of economic resilience in the study area changed from the transformation of industrial structure and the improvement of innovation level to multi-factors. Among them, residents' income, market scale, government regulation ability, industrial technology level are the key factors to promote the evolution of economic resilience in the study area. (3) The transformation of industrial diversification is the direct driving force for the improvement of economic resilience in the study area, and the evolution of the study area to a higher level of urban life stage is driven by multiple factors. When the pressure factor is eliminated, the urban state is adjusted and the response mode is optimized, the economic resilience will promote the "path breakthrough" of the industry by activating the industrial factors and balancing the driving force, and then evolve into a higher-level state, so as to promote the high-quality development of resource-exhausted cities.