Legal analysis: a contract can take effect even if it is not signed by law. The two parties have drawn up a contract. If one party has fulfilled its main obligations and is accepted by the other party without signing it, then the contract is established. In this case, the contract takes effect when it is established. 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. Since it is a contract, it needs to be signed by both parties.

Legal basis: Civil Code of People's Republic of China (PRC).

Article 143 A civil juristic act that meets the following conditions is valid:

(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 Where the parties conclude a contract in the form of a contract, the contract is formed 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.

Article 491 The parties entered into a contract in the form of data messages. It is also required to sign a confirmation letter, and the contract is established when the confirmation letter is signed.

If the information of a commodity or service released by one party through information networks such as the Internet meets the conditions of the offer, the contract is established when the other party successfully selects the commodity or service and submits the order, unless otherwise agreed by the parties.