Abstract: The frequent loopholes in the regulation of collection and storage in procurement affect the regulation effect of grain market and national food security,so doing a good job of the internal supervision of the collection and storage of procurement is related to the vital interests of grain farmers, the effect of national grain macro-control and national food security.The vertical management system of China′s grain procurement policy actually constitutes two levels of principal-agent structure.By building a three-tier management model consisting of “Government-China Grain Reserve-Agent companies”,the optimal regulation rules and collusion-proof contract are deduced. The theoretical analysis shows that information rent becomes the basis of rent-seeking from grain storage on behalf of warehouse under the condition of limited government supervision ability.In order to prevent collusion and guide enterprises to regulate storage, the government needs to compensate for the loss of utility caused by the non-collusion, or the amount of government fines must be higher than its fair income. The practical constraints such as cost balance of grain storage, conflict of storage objectives and reverse incentives will lead to the weakening of the effectiveness of government supervision.

Key words: grain procurement, principal-agent structure, information rents, collusion proof