Abstract: The Three-River-Source area is an area of serious freeze-thaw erosion with high altitude, latitude and low temperature, so it plays a positive role on putting forward some suitable ecological environment plans and protection measures to carry out research of freeze-thaw erosion. Using normalization method and evaluation model, this paper takes annual temperature range, precipitation, slope, vegetation coverage and solar radiation as indexes to evaluate freeze-thaw erosion intensity. The results show that: (1) Freeze-thaw erosion is widely distributed in this area, accounting for 75.7% of total area and the largest one is Yangtze River; (2) Though the three areas are most covered by moderate erosion, they are different in proportion of five classes in each basin and in proportion of five classes in three basins, and in general Yangtze River is the most serious area; (3) The spatial distribution seems to change from low to high alternatively as zonal distribution, but the determinant factor is different in the east and west. The west zone is influenced by vegetation coverage and solar radiation, the east zone is influenced by precipitation, slope and solar radiation, and the middle of this area is influenced by all those factors.