Abstract: The Yangtze River is one of the most important rivers in china and the annual soil erosion amount is about 2.4 billion tons. The serious erosion caused poor soil in upstream and frequent flood disaster in middle and lower reaches. As the major ecological problem of river basin, the soil erosion has become an important factor which restricts the regional development, and analyzing the soil conservation has become the focus of scholar's study. But a lot of soil conservation researches about the Yangtze Basin involved only the upstream. In this paper, the soil conservation ability of the whole Yangtze Basin was calculated by applying the Universal Soil Loss Equation (USLE) and its spatial-temporal distribution characteristics were analyzed by using Moran's I index and linear regression coefficient method. There are five factors in the USLE: R, K, LS, C, P. The R value was computed by using the daily rainfall data provided by the meteorological station in and around the study area. Among this process, the spatial interpolation had to be done. By access to relevant literature, the parameters in K model were obtained. Then, the K factor value was calculated according to the land use data. In Arcmap spatial analysis tool, gradient and slope length was calculated by computing DEM, and then got LS factor. The C factor value was got by calculating MODIS-NDVI data which download from NASA web site. According to the statistic values of P in different land use, the P factor was determined. Before calculate the soil conservation with GIS, all of these factors in USLE should be converted to the raster data with same projection and resolution. Based on the results of USLE, the spatial analysis with Moran's I index can be achieved by GeoDa and the linear regression coefficient method which was used to demonstrated the temporal dynamics can be carried out on GIS. The results showed that: (1) The amount of soil conservation in the estuary and source area of the Yangtze River was the lowest (≤560 t/hm²), while the high levels of soil conservation (≥ 2 400 t/hm²) area located in the upstream around Sichuan Basin, as well as the south of middle and lower reaches; (2) The inter-city soil conservation amount was highly auto-related. The regions of "L-L" type were found mainly in the source and estuary area of the Yangtze River and west of Wuhan; the cities of "H-H" type were mainly in the upper reaches of the Yangtze River and the south of Jiangxi; (3) The area where soil conservation quantity showed a trend of increase accounted for 62%. And the regions that presented rapidly increasing trend (b>5) distributed in the southern of Shaanxi, northwestern of Hunan, eastern of Jiangxi and eastern of Sichuan. The falling trend area accounted for 38%, mainly in the upper reaches of the Yangtze and south of middle and lower reaches.

Key words: soil conservation, spatial autocorrelation, linear regression coefficients, Yangtze Basin