Based on the injection carrier diffusion equation, dynamic characteristics of the crescent GaAs/(GaAl)As lasers integrated with buried passive waveguide have been analysed by using Eunge-Kutta and Simpson numerical method. Effects of structure parameters (such as central thickness do of the active layer, stripe width S, channel width W, and carrier diffusion length LD) on the threshold current Ith or threshold current density Jth are analysed. According to the analysis, in order to reduce the threshold current or threshold density, the ohanriel width W must be reduced to 2~4 μm and the stripe width S must be less than 5 μm. A cavity length L=350 and a thickness d0=0.17 μm are reasonably recoromended. Centers of non-radiative recombination should be reduced, the more the better. In this way, optimum results can be reached.　We also discuss the way to improve device quality and device structure in this paper.