The purchase contract is only valid if it is stamped. According to relevant legal provisions, if the parties conclude a contract in written form, the contract will be established and effective when all parties to the written contract sign, seal or fingerprint, unless otherwise provided by law. Article 490 of the "People's Republic of China" and the Civil Code: If the parties conclude a contract in the form of a contract, the contract shall be established when both parties sign, seal or fingerprint. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it. Article 502 A contract established in accordance with the law shall take effect from the time of its establishment, unless otherwise provided by law or otherwise agreed upon by the parties. In accordance with the provisions of laws and administrative regulations, if the contract should be subject to approval and other procedures, the provisions shall be followed. If the failure to go through approval and other procedures affects the effectiveness of the contract, it will not affect the effectiveness of the contract's obligation clauses such as submission for approval and related clauses. If the party that should go through the application approval and other procedures fails to perform its obligations, the other party may request that it bear liability for violating such obligations. In accordance with the provisions of laws and administrative regulations, if the modification, transfer, termination, etc. of a contract require approval and other procedures, the provisions of the preceding paragraph shall apply.