A game-theorized analysis of strategic alliances reveals significance of trust among partners in alliances and,based on this,this life-cycle function of the alliances is endogenous result in the process of repeated games.The research result shows that the life-cycle of the alliances in the moral hazard cases is a result of strategic choice of the alliance members and the utility level under mutual intraction in one-shot game and that,in inverse selection cases,the expected life-cycle of the alliance is a function of social average credit level,the endurance coefficient of the enterprises and different strategic combinations.