Abstract: By introducing the GNBS&formal fixed price contract into the two-stage farm produce supply chain relational contract,the paper analysed the roles of NBS&formal price contract(as the way to deal with disputation) in inspiring the farmer's relational specific investment,and the formal price contract's roles under relational specific investment's different impacts on the product value on external markets.The results show that,when GNBS as a way of solution to the disputation,the self-enforcement condition of relational contract relates to the value of product,the specificity of the product and the share of the residual of farmer;the formal fixed price contract is contributive to the self-enforcement of relational contract under specifically condition.

Key words: farmer produce supply chain, relatio nal co ntract, GNBS&formal price contract, stability of contract