Legal analysis: the contract was signed under a pseudonym, and the contract is invalid. According to relevant laws and regulations, it is fraudulent to sign a contract without using your real name. However, if the signature pen name does not match the household registration, it belongs to other names used to express the meaning of the actor in daily activities. If the signing behavior is the expression of the actor's true meaning, and the other party does not violate the true meaning, the signed contract shall be a valid contract agreed by both parties.

Legal basis: Article 148 of the Civil Code of People's Republic of China (PRC) * * * Where a party commits a civil legal act that makes his will express against his true meaning by fraudulent means, the defrauded party has the right to request the people's court or an arbitration institution to cancel it.