Legal analysis: China's laws stipulate that "if the parties conclude a contract in the form of a contract, the contract will be established when both parties sign or seal it", that is to say, the law does not require that the official seal must be affixed at the same time as the signature, and both must be complete. Instead, the parties are required to sign or affix their official seals, and there must be one of them.

legal basis: article 49 of the civil code of the people's Republic of China. if the parties conclude a contract in the form of a contract, the contract shall be formed when all the parties sign, seal or fingerprint it. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it.

a contract shall be concluded in writing as stipulated by laws and administrative regulations or agreed by the parties. if the parties fail to do so in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.