Legal Analysis: Valid. Under normal circumstances, a contract with only a signature and no seal should be deemed valid.

In the process of signing a contract, after the offer and acceptance, both parties have expressed the same intention, and the contract can be established.

The conditions for the validity of the contract include the following three contents:

1. The parties have the corresponding ability to conclude the contract.

2. The meaning is true.

3. Does not violate the law and social public interests.

The effective core content of a contract is the agreement of both parties, not the formal seal.

Legal basis: Article 502 of the "People's Republic of China and Civil Code" A contract established in accordance with the law shall take effect from the time of establishment, unless otherwise provided by law or otherwise agreed by the parties.