Abstract: Abstract：This paper analyzes the theoretical basis of bank insurance interaction and the internal logic of its impact on credit rationing, demonstrates the possible path for bank insurance interaction to play the role of mortgage guarantee replacement in agricultural insurance,summarizes the current situation of China′s Bank Insurance interactive pilot, and puts forward the necessary conditions and improvement measures for policy based agricultural insurance to effectively alleviate the credit rationing of farmers combined with the macro data and micro survey data.The research shows that the level of policy based agricultural insurance is low and the scope of insurance is single, the relationship between insurance compensation and risk is weak, the mechanism of information sharing and risk sharing is not fully established, and the bank does not have the absolute control right of the first loss payer;the basic terms, risk relevance and advanced terms of policy insurance cannot fit basic conditions and internal logic of bank mortgage guarantee role of insurance interaction in agricultural insurance.Therefore, index insurance should be taken as the basic agricultural insurance type of bank insurance interaction, and the first payor of insurance should be the bank, so as to realize the efficient information sharing and risk sharing among the subjects of bank insurance interaction.