Abstract: The changes of the plant diversity under the different desertification controlling measures will contribute to make countermeasures and measures of desertification combating and controlling. The plant diversity of grassland community under the different desertification controlling measures (by converting cropland to forests, artificial fencing and discontinuing farming and letting go out of cultivation) in Yanchi County, Ningxia Hui Autonomous Region was measured by using the methods of α-diversity index (including Shannon-Wiener index, Simpson index, J_sw and J_s which are community evenness indces) and β-diversity index (measured by similarity coefficients). Compared with the different fixed sample plot observation data in 2002 and 2003, the results show that α-diversity of studied plots increased in varying degree in 2003. By means of comparing beta index, the results also show that the species composition of experimented plots have changed to various extent. In addition, the main causes why the plant diversity in Yanchi County became better than ever is also presented.