From 2002 to 2003, based on the investigation of sample plots and stem analysis of remained plantation communities in the areas of returning farm to forest in 1980's in Datong county, Qinhai Province, this paper studies tree productivity and moisture potential productivity of six types of plantation on the land of returning farm to forest，such as Green Poplar (Populus cathayana Rehd.) and shrub mixed forest, Asia White Birch (Betula platyphylla Suk.) and China Spruce (Picea asperata Mast.) mixed forest, Dahurian Larch (Larix gmeini Rupr) pure forest, China Spruce pure forest and Asia White Birch pure forest and so on. The results show that: in sub-humid region of Loess Plateaus, 3000 per hmP 2 Pis a proper standard of planting density. At present lever of technique and economy, the productivity index of Green Poplar and shrub mixed forest, Asia White Birch pure forest, China Spruce pure forest and Asia White Birch and China Spruce mixed forest with the density of 2100-3333 per hmP 2 P can be served as potential productivity standard of actual biomass of arbor established forest under the condition of local normal planting techniques. In sub-humid area, it is adopted Thornthwaite Model to estimate plant climate potential productivity which is about 8462kg/(hmP 2 P﹒a) in this area. The actual potential water productive efficiency of Purplecone Spruce (Picea purpurea Mast.) and Asia White Birch pure established forest are 17.22 and 22.14kg/(mm﹒hmP 2 P﹒a) respectively, and that of Green Poplar and shrub mixed established forest and Asia White Birch and China Spruce mixed established forest are 21.14 and 19.09kg/(mm.hmP 2 P.a) respectively. The potential productivity of Green Poplar and shrub mixed forest, Asia White Birch and China Spruce mixed forest, China Spruce pure forest and Asia White Birch pure forest which have grown into forest with the density of 3000 per hmP 2 P have attained or closed to that of local climax community, which is local maximum tree productivity at present level of technique and economy. These types of forestation models are the developing direction of the returning farm to forest project.