Legal analysis: After the parties sign the bill, the bill will become legally effective, and the bill can be used as a voucher unless there is evidence to prove that the bill is wrong. Declarations that meet the following conditions have legal effect: 1. Signed by the representatives of Party A and Party B and stamped with the official seal of the company; 2. The representatives of Party A and Party B shall sign and affix the special seal for corporate finance; Three. Signature of legal representatives of both parties.

Legal basis: Article 143 of the Civil Law of People's Republic of China (PRC) is valid for civil juristic acts that meet the following conditions: (1) The actor has corresponding capacity for civil conduct; (2) the meaning is true; (three) does not violate the mandatory provisions of laws and administrative regulations, and does not violate public order and good customs.

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.