The use of the double-rectangular-prism (DRP) cavity and the self-aligned feature of the rectangular prism (RP) make laser insensitive to shock, vibration and temperature fluctuations. When the laser repetition rate is 20 Hz, the output energy is 60 mJ, the pulse width is 11 ns, the divergence angle after ten times of beams expansion is 0.11 mrad, and the optical axis drift is less than 5 μrad in 30 s. The DRP cavity can effectively enhance the stability of laser optical axis. With a polarization coupling output, the coupling output rate is determined by the wave plate parameter and the RP material. Based on the theoretical study and the electromechanical integration design, a laser with high optical axis stability is successfully developed. The study has certain guiding significance for both the parameter design of DRP cavity and the engineering application of lasers with high optical axis stability.