As one of the key steps of phase measuring deflectometry (PMD), surface reconstruction is of great significance to realize high precision surface reconstruction. Considering the actual situation, the sampling points on the surface to be measured are not uniformly distributed. Given this non-uniform meshes distribution, a novel method was presented based on subset interpolation. The innovative method of surface reconstruction is realized by the improved Lagrange polynomials. According to the numerical simulation and analysis, the simulation results show that the proposed reconstruction method is appropriate for the reconstruction of various surfaces in non-uniform meshes. Under the conditions of the simulation, the accuracy of surface reconstruction of the traditional method is in the order of 1×10-2 mm, while the accuracy of surface reconstruction of the improved method is as high as 1×10-7 mm.