The work aims to further maximize the profit of the quantity flexibility contract for agricultural product supply chain. Under the condition of random market demand, a quantity flexibility contract model for agricultural product supply chain composed of suppliers and retailers was established by considering the sales effort and transportation time as the key variables affecting the demand. Based on this model, reward and punishment strategy was introduced to realize the consistency and effectiveness of agricultural product supply chain flexibility contract. Combined with the characteristics of agricultural products, through the specific model optimization method and example analysis, the optimal value and the correlation between each variable and the optimal sales effort level, the optimal transportation time, the optimal order volume and the overall agricultural product supply chain profit were obtained. The flexibility contract of agricultural product supply chain can realize the profit maximization under the coordination, which has an important theoretical and practical value for the agricultural business subject enterprises to carry out the flexible research on agricultural product supply chain.