Abstract: This paper presents a cooperative game method for structural optimization design with multiple objectives. It also presents the game description about multi-objective problems i.e. decomposing design variable assembly into a stratagem set of all the game players. This method adopts conspiring cooperative model, which complies with the agreement of “I have you with me and you have me with you”. It combines absolute benefits with relative benefits to be the payoff function of game players. Single objective optimization is carried on in each game player’s strategy set to obtain the player’s optimal countermeasure to the other players, by taking his payoff as the objective function. The entire optimal countermeasures form a new game strategy set. The game equilibrium solution will be obtained finally by playing the game several times, according to the convergence criterion. The design of a four-bar truss and an arch dam demonstrates the efficiency and reliability of the cooperative game method.