Nonlinear polarization rotation mode-locking technique is one of the efficient ways for fiber lasers to generate ultra-short pulses.It has attracted significant attention because of the simplicity,compactness and high reliability.In this paper,using nonlinear polarization rotation technique,the laser delivers the solitary pulses with the duration of 1.35 ps and the fundamental repetition rate of 9.49 MHz at 1557.7 nm.In addition,the generation of solitary pulses is simulated by the coupled Ginzburg-Landau equation and the build-up of the mode locking is also analyzed in the time and spectral domains.Numerical simulations and analysis confirm the experimental observations.These results help to deepen the understanding of soliton mode locking dynamics.