Abstract: laser system with high output stability was designed for three-stage optical parametric chirped-pulse amplification(OPCPA). The PPKTP crystal was chosed as the first-stage gain medium, the LBO and the KDP crystal were used for the second-stage and third-stage, respectively. Through numerical simulations, the output gain and gain stability were obtained for three stage optical parametric chirped pulse saturated amplification. In the case of pumping intensity jitter less than 6%, the output gain jitter of the OPCPA system is less than 1%. In the case of PPKTP crystal chosed as the first-stage quasi-phase matching gain medium, with a pump peak intensity of 30MW/cm2, which is far from damaging the PPKTP crystal, the saturation amplificated gain is 2×105 and the conversion efficiency is 20%.