10 different future land cover pattern scenarios with slope criteria were built based on local ecological policies in the watershed of Ertan reservoir. The responses of 3 different ecosystem regulating services which were avoiding reservoir sedimentation, avoiding nonpoint source pollution of aquatic environment and water supply and energy produced and its economic value to future land cover pattern were studied. The service benefit of various pattern scenarios was weighed by integrating the change of income of agriculture, forestry and animal husbandry. The scenario which let the well-being of related groups to maximal increase was selected. The results showed:
1) The existing land cover pattern was incongruous to exerting the ability of avoiding reservoir sedimentation. The land cover pattern changed according to the national policies for returning farmland to forests was in favor of avoiding riverway and reservoir sedimentation. The value of sediment retention's ranks was contrary to sediment delivery. The value of sediment retention followed the rules of "the area percent of forest and grassland increasing as the value of sediment retention". Along with the increase of total sediment delivery, the high sediment delivery cells spread out from the region around the reservoir to the middle and upper reaches of Yalong river.
2) The national policies for returning farmland to forests guided the land cover changes were based on the slope ranks. It was unsuitable to avoiding phosphorus nonpoint source pollution of aquatic environment in watershed. The ranks of phosphorus delivery were completely in line with the value of filtering phosphorus pollution except scenario 10 which was all covered by unused land. The law was farmland>grassland>forest. Along with the increase of total phosphorus pollution delivery, the high phosphorus pollution delivery cells spread out from the source region and big river bend of Yalong river basin to the whole network of rivers of watershed except scenario 10.
3) Along with the increase of the forest area percent, the total net present value (NPV) of energy produced in watershed decreased. Along with the increase of total net present value (NPV) of energy produced, the high NPV cells spreaded out from the eastern of Mianning and Xide county to the southeast of whole watershed and the lower reaches of Yalong river.
4) From the viewpoint of lightening the negative effect to environment and letting the well-being of related groups be maximal increase, The quantity of aggregative indicator on scenario 5 that 6° slope was a threshold in determining farmland and forest cover and scenario 3 that 6° and 15° slope were threshold in determining farmland, grassland and forest cover increased at the highest extent except the extreme scenarios.