In this paper, the maternal detecting system, which main functions were to monitor the variations of lands areas, was rebuilt by means of the mass sampling technique. This new rebuilt system may raise the accuracy of the surveyed land areas. The surveyed land area increase from one land area to four. The system may reduce the least surveyed land area from 30 thousand hectare to 7 thousand hectare within a county. These results were proved by the simulating trial information of masses. By experiments of the 10 distances on the 50 detected wheat points, 111.11 metres is selected to be the best distance.This new system made it possible to detect variations of the more agricultural resources, for example land areas, crops yields, soil water etc.