The quantitative assessment on spatial pattern of watershed ecosystem service and water conservation function has important signifance for the sustainable development of water source areas and the establishment of ecological compensation mechanism. Based on the data of land use, meteorology and soil in the study area, the paper used InVEST model to evaluate the amount of water of ecological system in Yuqiao watershed, and quantitatively assess the spatial distribution feature of water supply ability in the whole basin. The result showed that when the Zhang coefficient is 3.2, the total water yield in the basin is 3.14 108 m3,the annual runoff depth is 161mm/a; in the point view of spatial distribution,there is a significant spatial heterogeneity for water supply yield in the basin. The southern and eastern-central plain areas of the basin have higher water volume supply per unit area.The ability of water supply in southern shore area of Yuqiao reservoir is higher than that in the northern shore area. Zunhua city and Jixian county contributes to 85% of total water .the comparison of water conservation capacity between different types of landscape indicated that the order of water supply ability from big to small is farmland>forest>artificial surfaces>bare land>shrub grassland.Farmland, forest and artificial surface contribute to 82% of total water.Therefore, the eastern-central plaint regions should be the key protected areas for water supply function and is the key area for the prevention and control of urban non-point source pollution.