Forest area in Liupan Mountains is important water conservation area of Loess Plateau. This area experienced large-scale afforestation during the past 3 decades, and the landscape patterns has been changed greatly. These changes have result in consequently changes of characteristics of main hydroecological progress and ecological function. Based on analysis of the dynamic and components characteristics of hydrological process, this paper discussed possible changes of landscape caused by afforestation and their hydroecological impact based on simulation results made by a distributed hydrological model TOPOG, in order to offer a hydroecological view for the undertaking afforestation activity in Liupan Mountains and Loess Plateau. The preliminary scenario simulation and analysis imply that total runoff at catchment outlet will decrease total runoff of catchment if increasing area of Larix principris-upprechtii woodland through cutting natural broadleaf woodland or reclamation of shrub patches. The decrease of total runoff can reach 28% when the area ratio of Larix principris-upprechtii patches enlarges from 11.5% to 58%. While reclamation of shrub patches also might reduce availability of water resources because runoff undulating will enlarge.