In this paper, dual semiconductor saturable absorber mirrors (SESAMs) are utilized to realize stable passively mode locked laser operation, and shorter and more stable picosecond pulses in long time are obtained compared with the case with single-SESAM mode locking. In theory, Haus master equation describing the mode locking dynamics of saturable absorber is numerically solved with split-step-Fourier transform method. The detailed dynamic pulse evolution process with dual-SESAM mode locking is simulated. The relationship between the pulse formation and two SESAM saturable absorption loss parameters q1 and q2 are analyzed. Also the mode locked pulse widths and stability region are calculated, and the numerical results are in agreement with the experimental results well.