A reliable design and optimization of laser diode end-pumped Yb:YAG disk pulsed laser with high peak power and high efficiency is investigated.Based on discussion of the energy storage and extraction in the gain medium firstly,and theoretical analysis and modeling the gain performance and thermal effects of gain medium,the process of the amplifier gain medium design and optimization is discussed and analyzed systematically.According to the analysis,a resultant laser amplifier with high peak pulse power and high efficiency is obtained,which is able to suppress sufficiently the parasitic oscillation and thermal effects.