Abstract: Based on cavity theory,the characteristics of dynamic stability zone of a parallel-concave laser cavity are analyzed in detail,taking account of thermal lens effect equivalent to convex lens.In general,the laser with parallel-concave cavity can operate in one of two dynamic stability zones.We found that,in a special case,the parallel-concave cavity has only one dynamic stability zone.According to theoretical analysis,we selected a set of cavity parameters and carried out the experiments,taking Nd:YAG as a exmple.The results show that the output power of laser increase with the pumping power in a rather wide range.