With the development of commodity economy, we have already realized that it is inadequate to apply the tort law to protect the third party.Foreign countries already have applied contractual liability to protect the third party’s interests.In China,the principle of contract relativity is the corner stone of contract law,legislation and judicial practice has not admitted that contract liability will be extended to the third party yet, and the third party’s interests can be only protected by the tort law.In order to protect the interests of the third party,we can learn from extraterritorial legislation to expand contractual liability to third party,and analyze from the expansion of contract effectiveness to the scope of application of third party and contract type expansion of contract effectiveness,and give third party relief approaches for the competition and cooperation of tort liability and contractual liability claim.