From the perspective of social e-commerce, this paper discusses the influencing factors and mechanism of purchase intention of agricultural products. Based on the stimulus–organism–response model, this paper constructs the relationship model of agricultural product characteristics, social trust, social stickiness, social support, social interaction, consumer perceived value and consumer purchase intention; the related hypotheses are found, and the hypothesis and the structural model are verified by analysing the data. The results show that the characteristics of agricultural products, social stickiness, social support, social interaction and consumer perceived value are the key factors that influence the purchase intention of agricultural products. Perceived value is the intermediary mechanism of social stickiness, social support, social interaction and purchase intention.