Abstract: A field monitoring system for gentle slopes,steep slopes and gentle slopes with grass coverage was established in expansive soil of Nanning,Guangxi,and the development of the deformation,water content and temperature for expansive soil slopes with the local atmosphere was measured by the six-parameter mini-environmental station,TDR system,oven-drying method,temperature sensors,inclinometer and settlement plates.The rainfall was considered as the most direct external factor of slope disasters and the evaporation effect was one of the important premises,while the wind velocity,net solar radiation,air temperature and relative humidity were indirect factors.The variation of soil temperature could reflect the behaviors of water content in different positions of slopes.The slope deformations were mainly concentrated in the surficial soil,and the position of the maximum deformation of slopes was in the middle part.The progressive failure occurred in the steep slopes.Grass coverage could not only maintain the water content of slope surface and reduce the erosion of precipitation,runoff and deformation,but also play a role of peak clipping and valley filling for soil temperature.