Abstract: Based on mode coordinate, the optimal vibration control of truss structure is designed. Using the approximately discrete method, the approximate solutions of structure closed-loop response are obtained. The approximate solutions can substitute for the exact solutions. The randomness of physical and geometric dimensions parameters of truss structure was considered and represented in the form of random factor. And then, the computational expressions of the mean value and the variance of the stochastic parameters structure closed-loop response under the optimal vibration control were derived by means of the random variable’s functional moment method. Finally, the influence of the randomness of structural physical and geometric dimensions parameters on the structure closed-loop response is analyzed by example with the method of this paper and the Monte Carlo method, validating the feasibility of this method discussed by this paper.