Abstract: FEM strength reduction method has been more widely used in the stability analysis of slope engineering rather than tunnel engineering. In this paper the FEM strength reduction method is adopted in a stability analysis and control of tunnel engineering, and a dynamic evaluation on the surrounding rock stability in whole construction process is proposed based on the safety factor. The dynamic controlling indexes of tunnel monitoring and measurement during construction are established by studying the deformation law of tunnel surrounding rocks. The analysis on calculation examples show that the dynamic evolution law of surrounding rock stability during construction can be mastered quantitatively and visually based on the safety factors of rock mass; the corresponding deformation control indexes can be determined for different construction stages under premise of meeting the stability requirements of surrounding rocks after installing primary support so as to overcome the limitation of taking the permissible displacement of surrounding rocks as the criteria of tunnel stability.