The stability of the four_mirror,five_mirror and seven- mirror folded cavity of CW Ti:sapphire laser is analyzed respectively and compared by using the computer which draws the stable range figure of resonator through running the program of C Language which is programmed according to the round-trip matrixes and the stable conditions and the astigmatic compensation conditions of resonator.

This text analyzed the losing steady characteristic and distortion of tire when it gets instable,found out the relation between the gradient angle and the azimuth angle?the distortion of tire,established uniform expression that he gradient angle has relation to the azimuth angle change,plotted the static stability district diagram,and pass the example to make the stability analysis.

Meanwhile,the regional crustal stability assessment zonation map of China should be compiled to build up the regional crustal stability national platform and to be adopted as the standards for land plan and engineering safety construction.