Legal analysis: The IOU is valid without the borrower, and the validity of the contract mainly depends on whether the signing of the contract belongs to the true intention of both parties and whether it violates the law. Whether the borrower signs or not does not affect the overall effectiveness of the contract. As long as the fact of borrowing itself exists and part of it is invalid, it can be supplemented later. A contract shall be in written form in accordance with the provisions of relevant laws and regulations or the agreement of the parties. If the parties have not concluded a contract in writing, but one party has fulfilled its main obligations and the other party has accepted it, the contract is established.

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. 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.