Desertification is one of the most serious environmental problems in the Qinghai Lake watershed. Desertification land had been increasing in the last several decades. In this paper, Landsat TM imageries are used to monitor the desertification land in 1977, 1987, 2000, 2004 and 2010, with the spatial analysis tool ArcMap software, we calculate the transfer matrixes and dynamic degree to analyze the temporal and spatial change of desertification types. The desertification land experienced the most significant expansion in 1980s and remained stable in the next 30 years. In particular, desertification land was during a increasing process in 1977-2000, while in 2000-2010, desertification land remained stable and partial reversion. Surface deposits of different desertification types were collected, and then grain size were measured, the results showed that fine particle matter and standard deviation decrease while coarse particle matter and the mean average grain diameter increased with the severity of desertification. The vegetation coverage may not coordinate with the grain size characteristics, so we should take grain size, soil nutrients, soil water conditions and so on into consideration when combating land desertification.