Based on determinations of organochlorine pesticide (OCPs) residuals in surface soils around the Guanting Reservoir, Beijing in 2003, 2007 and 2009, the Cardinal-spline interpolation method was used to make up the data of the missing years for prediction of data on OCP residual in 2010. On such a basis, analysis was done for temporal variation of OCPs concentrations at the sampling points and its causes and affecting factors of the degradation of OCPs. By referencing the National Standard for Soil Environment Quality, surface soils in the region were evaluated for OCPs pollution. Results show that 1) OCPs concentrations at some sample sites have rebounded, which suggests existence of exogenous inputs; 2) soil texture is a major factor affecting OCPs degradation rate while vegetation on-site is not; 3) ∑HCH was found below the bottom limit of Grade I criteria of the national standard at all sample sites from 2003 to 2009, and ∑DDT was declining and fell within Grade I criteria of the national standard in 2009; and 4) it is predicted that in 2010, ∑HCH will basically remain stable and ∑DDT go on declining.