Legal analysis
A contract signed and sealed unilaterally is generally invalid in law. However, if the signed and sealed party takes the text as a valid offer, as long as the unsigned counterpart makes a valid commitment to the text, the contract will be established according to law and take effect without violating the legal provisions. If this contract is a written contract with only the signature of Party B, but not the signature and seal of Party A, this contract is invalid. If the contract is electronic, a confirmation letter must be signed in advance, otherwise the contract will be invalid. A contract sealed by Party A and not sealed by Party B is invalid. Because the contract is a legal act of both parties, it must be signed and sealed by both parties to take effect, and the contract signed and sealed unilaterally is not established. However, before signing or sealing, one party has fulfilled its main obligations and the other party accepts it, and the contract is established. After the contract is established, whether it can produce the legal effect and legal consequences expected by the parties depends on whether the contract has the effective elements. The effectiveness of a contract shall meet the following conditions: (1) The parties to the contract have corresponding capacity for civil rights and capacity for civil conduct; (2) The parties to the contract expressed their true meaning; (3) It does not violate the law or public interests; (4) Formal requirements required for the contract to take effect as stipulated by laws and administrative regulations.
legal ground
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.