A contract with an official seal and no legal person's signature is valid. According to the law, if the parties conclude a contract in the form of a contract, the contract will be established when the parties sign, seal or press their fingerprints. Therefore, when signing a contract, the parties can choose one of signature, seal and fingerprint, and they don't have to sign and seal at the same time.

Legal objectivity:

Article 490 of the Civil Code of People's Republic of China (PRC): If the parties conclude a contract in the form of a contract, the contract is concluded when 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 written form as stipulated by laws, administrative regulations or agreed by the parties. If the parties do not do this in writing, but one party has fulfilled its main obligations and the other party accepts it, the contract is established.