中文摘要：

在原奶购销契约的案例中，虽然公司和农户双方都做出了专用性投资，但契约仍不能持久稳定。数学模型证明，双边专用性投资未能稳定奶业契约的原因是双方不平衡的再谈判力，当面对市场风险时再谈判力弱势一方将处于持续亏损状态，最终因破产而导致契约关系的失败。从契约双方的潜在可替代交易量和交易转换成本两方面去平衡双方的再谈判力，是专用性投资后进一步稳定契约关系的关键。

英文摘要：

In case of raw milk transactions, contracts between dairy farmers and corporations are unstable even though they have made specific investment. Mathematical models prove that it is non-symmetry of power in renegotiation that makes the contract unstable after the specific investment on both sides. When facing the market risks, the weak party will suffer continuous losses and finally go bankrupt, which will lead to invalidation of the contract. After two-sided specific investment, to balance the power in renegotiation is the key to stabilize the relationship of the contract by adjusting the potential alternative transactions and switching cost.