In order to obtain an airborne laser radiator with compact structure, high beam quality and good optical stability, LD end-pumped configuration and orthogonal porro prism cavity technology were used to study this type of laser. Based on Jones matrix theory, the principle of realizing Q-switched with special wave-plate was analyzed, and the cavity was controlled to the large fundamental mode size through the design of Porro prism cavity mirror with suitable curvature. The results show that the laser output with single pulse energy of 72.2 mJ and beam quality of Mx2=8 and My2=6 can be obtained at 20 Hz repetition frequency under the condition of orthogonal polarization closed state. Based on the Porro prism material of K9 glass, 0.648λ wave-plate was used for Q-switched closed state. Under the working repetition frequency of 20 Hz, a high beam quality output with single pulse energy of 80 mJ, beam quality of Mx2=5.7 and My2=4.8 is obtained .The divergence angles of the laser in the x- and y-direction are 1.65 mrad and 1.35 mrad respectively. This result is helpful for the research and development of high performance miniaturized lasers.