Where the parties enter into a contract in the form of a written contract, the contract is formed when each party affixes its signature, seal or fingerprint. If a party has performed its principal obligation before the signature, seal or fingerprint is affixed, the contract is formed when the other party accepts the performance. 当事人采用合同书形式订立合同的，自当事人均签名、盖章或者按指印时合同成立。在签名、盖章或者按指印之前，当事人一方已经履行主要义务，对方接受时，该合同成立。 If any law or administrative regulation requires that or the parties agrees that a contract should be entered into in written form, but the parties fail to enter into the contract in written form and one party has performed the principal obligation, the contract is formed when the other party accepts the performance. 法律、行政法规规定或者当事人约定合同应当采用书面形式订立，当事人未采用书面形式但是一方已经履行主要义务，对方接受时，该合同成立。