[Objective] Identifying priority watershed for soil and water conservation is a premise for the watershed planning. The purpose of this study was to determine the scale effect of identifying the priority watershed.[Methods] Taking Hechuan District, Chongqing Ciyt as an example, the comprehensive indexes was calculated by using the proportion of soil and water loss area, the proportion of land use and the average slope of the basin for identifying the priority watershed. The scale changes from level Ⅰ (with watershed area ranged from 50 to 300 km²), level Ⅱ (10~50 km²), level Ⅲ (1~10 km²), level Ⅳ (0.1~1 km²) and level Ⅴ (0.01~0.1 km²).[Results] The watershed scale had obvious effect on the identification of priority watershed. The distribution of priority watershed derived from level Ⅳ and Ⅴ was more similar to that of soil erosion area derived from soil erosion map in the Hechuan District. The average percentage area of soil loss, the mean proportion of cropland and mining land, and average slope gradient of the priority watersheds from the level Ⅳ and Ⅴ were clearly greater than those from the other levels.[Conclusion] The number of the priority watershed from the level Ⅳ was less than that from the level Ⅴ. The level Ⅳ was the best watershed scale for identifying the priority watersheds. It will aid in the management and planning of the priority watershed based on the level Ⅳ watershed.