Legal analysis: Generally speaking, a rental contract is not valid if it is not signed. If the lessee has fulfilled its main obligation, that is, paying the rent, and the lessor accepts it, that is, collects the rent, and gives the keys to the lessee, the contract is deemed to be established. For a contract established in accordance with the law, it becomes effective from the time of its establishment. Except for some circumstances that render the contract invalid as stipulated in the law, it is all valid.

Legal basis: Article 490 of the "People's Republic of China and Civil Code" Where the parties conclude a contract in the form of a contract, the contract is established when both parties sign, seal or fingerprint. Before signing, sealing or fingerprinting, one party has performed its main obligations and the contract is established when the other party accepts it.

Laws, administrative regulations or the parties agree that a contract should be concluded in writing. If the parties do not do so in writing but one party has performed its main obligations and the other party accepts it, the contract is established.