Legal analysis: A contract signed by Party B but not signed by Party A generally has no legal effect. If the contract does not require approval and other formalities to take effect, it will generally take effect when signed by all parties; Or if one party has fulfilled the main obligations of the contract, it will take effect when the other party accepts it.

Legal basis: Article 490 of the Civil Code of People's Republic of China (PRC). If the parties enter into a contract in the form of a contract, the contract shall be established when the parties sign, seal or press their fingerprints. Before signing, sealing or fingerprinting, one party has fulfilled its main obligations, and the contract is established when the other party accepts it.