The premise of the validity of a civil act is that it conforms to the law, that is, it does not violate the prohibition and mandatory provisions of the law, and it means that it truly abides by the principle of good faith. As long as the signed contract can embody the principle of protecting the rights and interests of all parties, the contractual relationship should be considered valid. As for whether the parties affix their official seals or sign, it is only a matter of form, because they only affix their seals but don't sign or just sign and don't stamp, and there is no opposite determination on the establishment and effectiveness of the contract.
Article 32 of the Contract Law of People's Republic of China (PRC) stipulates that if the parties conclude a contract in the form of a contract, the contract is established when both parties sign or seal it.