This study employs the Stackelberg game model to explore an innovative financing model where the retailer directly borrows from the bank under conditions of symmetric information. Diverging from traditional research, this study uniquely incorporates the concept of the margin rate into the decentralised decision analysis among retailer, supplier, and bank. The finding indicates that the capital of the retailer and margin rate significantly influence financing decisions within the supply chain, thereby impacting profitability for all stakeholders. Specifically, we find that the margin rate plays a crucial role in optimising retailer financing decisions, supplier pricing strategies, and bank risk management. These insights offer a fresh perspective for banks to establish appropriate margin rates and loan interest rates, effectively managing loan risks and maximising supply chain profitability.