Abstract: According to the optimization principle for diodepumped laser, one kind of mini diode-pumped laser for seed-injection is designed. Using the numerical method, the optimized design is presented laser gain media, coupling system and resonant cavity. The seed laser beam from mini diodepumped laser was injected into Q-switched laser and output characteristics of Q-switched laser were studied. The experiment results show that this laser is stable, with high beam quality and small light beam divergence. The lightlight efficiency is 17.4% and slope efficiency is 24%. The output power of this laser is about 80mW. The buildup time of laser pulse in power oscillator decreases by 40ns and the injectedseed laser field improve the distribution of output laser field．