The World Heritage Fujian Earth Buildings are located in China’s southeast coastal area where is frequently suffered from typhoon and severe weather, the annual amount of rainfall can be as much as 1600 mm.Whenever typhoon landed, the gustiness, gathering with the torrential rain, tends to erode and cause damages to these Earth Buildings, with that, the wind-driven rain’s erosion of the rammed earth wall has become the main form causing such damages. The accurate simulation of numerical wind tunnel can be completed by the adoption of methods of CFD numerical simulation and wind tunnel test, according to the analysis of the raindrops’ motion form and the rainfall characteristics under the effect of the wind-driven rain. Considering the various combinative conditions of the rain strength and wind speed based on the numerical wind field and rainfall model, followed by analyzing the erosion damage of the rammed earth wall caused by the weather beaten, in such way, whose inherent regularity can be revealed. The last step is to predict the annual range of average erosion damage which is from 0.4 mm to 2.6 mm by the calculation example based on the local meteorological statistical data. The result will provide the earth buildings’ maintenance reinforcement and exploitation with scientific basis, and provide the other rammed earth architecture with reference as well.