After five models of converting cropland to forest in low-mountain and high-mountain areas in Beichuanhe watershed of Datong county of Qinghai province were selected respectively,the hydrology effects were analyzed.The water-holding capacity of the canopy,litter layer and soil in different species arrangement models were increased along with biomass of the canopy and existent mass of litter layer.The water-holding capacity of soil was the biggest(>97%) in the total water-holding capacity of forest.The more the total pore space,the bigger the final infiltration rates.In the low-hill area,the total water-holding capacity of the canopy and litter layer of model D(Hippophae rhamnoides)was the biggest,that was 1.43 mm and 1.87 mm respectively;The total water-holding capacity of soil and forest of model C(Populus cathayana Lycium barbarum),which was 327.88 mm and 329.07 mm respectively,ranks first place in different models of species distribution.The final infiltration rate of model A(Paeonia veitchii) is better than others,which is 4.8 mm/min.In the remote-hill area,the total water-holding capacity of canopy,litter layer,soil and forest of model F(Picea crassifolia) ranks first place in different models, which was 2.37 mm,6.24 mm,323.3 mm and 331.91 mm respectively,and the final infiltration rate of soil is 6.8 mm/min.