This paper analysis the domestic and overseas literatures of the failure and policy subsidy in crop insurance market. It believes that take the Character of quasi-public goods and external effect that the crop insurance produce as an argument of the failure of crop insurance market and policy subsidy is not strictness. It puts forward the main basis of the policy subsidy of crop insurance theory is the degree of policy subsidy that the crop insurance need depends on the role of it as a support-agriculture tool compare with other support-agriculture policies.