In recent years, e-commerce enterprises have begun leveraging digital platforms to explore agricultural supply chain business. This paper considers the loss aversion behavior of farmers and compares three financing models: Bank financing, platform direct financing, and platform guarantee financing. The results show that the platform’s choice of financing model is highly dependent on farmers’ loss aversion and financial constraints. For the platform, when farmers exhibit high loss aversion and low capital scarcity, platform-guarantee financing is optimal; Otherwise, platform-direct financing is optimal. For both the farmers and the whole supply chain, platform-guarantee financing is optimal. Overall, when farmers exhibit high loss aversion and low capital scarcity, platform-guarantee financing can realize a win-win situation for both the platform and the farmers and improve the efficiency of the agricultural supply chain. The results of the study provide an explanation for the practical application of platform-guarantee financing, and offer a reference for managerial decision-making in similar businesses.