Land desertification in Songnen Plain was studied using satellite images from 1975, 1990, and 2001. By analyzing the data with GIS methods, researchers found that from 1975 to 1990, desertification expanded by 1368931hm^2, with stronger deterioration at the edges. However, from 1990 to 2001, desertification decreased by 297867hm^2, showing a reversal trend, especially at the edges. Overall, the trend of land desertification in Songnen Plain has been kept within limits over the past 30 years.