Abstract:In order to improve the stability ofmilitary solid-state laser, a alignment-free directional prism resonator , u-sing g3 parametric equivalent resonatormethod,which keep TEM00 mode workingwhen the focus length of the thermal lens kept in a certain range,was designed. The experimental resultwas found to be very close to the theoretical analy- sis, and meet the request of high stability and high beam quality to military laser equipment.