A numerical model for self-similar pulse nonlinear polarization rotation mode-locked fiber laser is built by utilizing coupled nonlinear Schrdinger equations （CNLSE）. In this model, the propagation of the pulse within single mode fiber is described by CNLSE. In the gain fiber, gain bandwidth and saturable gain are both considered. Other optical components which implement NPE mode-locking are modeled by transfer matrixes. According to the optimized net cavity dispersion and length of the cavity, the evolution of the pulse along the cavity is simulated. At the same time, characteristics and the typical regime of the self-similar pulse are found. The simulation results show that pulse with 7 nJ energy, 11 ps duration, linear chirped, and of parabolic shape occurs within the optimized self-similar regime. The characteristics of the laser with different dispersion are compared. The influence of the third order dispersion on the laser is simulated.