Based on meshing method， the effect of double freeform surface lens with extended light source was firstly analyzed， in which the double freeform surface lens was designed with point light source and different illumination distribution. An optimized illumination distribution for point light source was then proposed， which could improve the uniformity of the extended light source from 46.27% to 77.30% along horizontal direction and from 28.05% to 70.25% along diagonal direction， especially for large distance-height ratio lens. The uniformity could be furtherly increased to 96.24% and 88.96% by applying microstructure on the bottom surface. The proposed design method could achieve a better lens profile for point light source， which could heavily reduce the optimization workload， shorten the development time， and present great practical value.