legal analysis: illegal. If you work for more than one month without signing a labor contract due to the reasons of the unit, you should pay double wages.

legal basis: article 3 of the labor contract law of the people's Republic of China

when concluding a labor contract, the principles of legality, fairness, equality, voluntariness, consensus, honesty and credibility should be followed. The labor contract concluded according to law is binding, and the employer and the employee shall perform the obligations stipulated in the labor contract.

article 11 to establish labor relations, a written labor contract shall be concluded. If a labor relationship has been established and a written labor contract has not been concluded at the same time, a written labor contract shall be concluded within one month from the date of employment. If the employer and the employee conclude a labor contract before employment, the labor relationship shall be established from the date of employment.

article 36 the employer and the employee may terminate the labor contract through consultation.