Based on the monthly mean temperature data of 39 meteorological stations in Jiangsu Province from 1957 to 2001 and Digital Elevation Model(DEM) data with resolution of 90 m,a geographical knowledge aided spatial interpolation model was introduced to improve the spatial interpolation result.Comparative analysis was conducted between the knowledge based spatial interpolation and traditional methods of Inverse Distance Weighting (IDW),CoKriging (CK),Ordinary Kriging(OK),Spline function(SPLINE) using the cross validation results,it was concluded that the range of the monthly temperature lapse rate was about 0.5-0.9 ℃/(100 m) in the research area,and the proposed interpolation method based on DEM was superior to other methods in both interpolation effect and accuracy.The monthly mean temperature distribution map with resolution of 90 m was established,which expressed the main trend of temperature changing with terrain and reflected the spatial variability of temperature.