This paper proposes a multiple repeat game algorithm based on credibility, calculates the credibility through the acting strategy of participators in each round of game, indicates that the acting strategy of the participators of next round is related to their credibility and that the unilaterally increasing of the participators’ gain can result in the decrease of their credibility according to the relative rewards and punishment mechanism based on the credibility, and proves that the repeat games ultimately trend to Pareto Optimality.