Abstract: The debtor's liability for the implementing aid-party is an important part of the system of civil law. There are some different ordains in various countries. This institution is the embodiment of the privity of contract and the principle of strict liability. The implementing aid-part includes agent and employee whose action shouldn' t be interfered by the debtor. The debtor assumes this liability when the implementing aid-part implements the contract. So we should learn from these countries. We should stipulate not only the limits of the third-party but also the types of the implementing aid-party and the conditions of this liability.