For a complex opto-mechanical system related with optics, mechanics, electronics, control, thermodynamics, gas, liquid, etc, it is an unsolved key problem that how to assess the performance of complicated opto-mechanical system. Herein, combined with Analytic Hierarchy Process(AHP) method, grey method, fuzzy method, etc., one intuitionistic G-factor is presented to evaluate the performance of the system. The G-factor has only one value and can be a direct token of the whole system. Through the statistic progress, it can compare single parameter with that of other system.