In the cooperation model of leading enterprise +farmer, channel stability is always a prominent problem. Based on previous researches, taking farmers in Hainan region as investigation object, the influence factors of channel stability of leading enterprise + farmer are studied by combining the background of formal contract and using the combination method of theory and demonstration. Contract item design, trading cost, product specificity, power structure, information asymmetry and social relationship are contained in analytic framework to establish theoretic model. Research results show that in formal channel management, when contract clause design is more explicit, product specificity is stronger, power structure is more balanced, information share degree is higher, and trading cost is lower, channel is more stable, and farmer’s willing to renew contract is stronger. Meanwhile, social relationship plays stronger regulation role.