Abstract: Laser cavity stability is a conventional and concerning subject from the birth of laser.With a "cat's eye" reflector as the reflecting mirror,the problems of laser adjustment and power stability can be solved.Comprehensive experiments are carried out in a half-external cavity He-Ne laser and the "cat's eye" reflector cavity,plane-concave mirror cavity and concave-concave mirror cavity.The results show that the use of the half-external "cat's eye" cavity can improve the laser stability and lower the power drift significantly.The adjustment problem is also considered and solved.A stable and adjustment-free He-Ne laser is finally realized,which exhibits remarkable advantages than the current He-Ne lasers.