The labor contract is signed once every few years, which is not stipulated by the law. The laborer can negotiate with the employer.
 An employer may choose to sign a labor contract with a worker once a year. However, when signing the third labor contract, the employee has the right to request to sign a non fixed term labor contract with the employer according to relevant regulations. If the employer and the employee agree through consultation, they can sign a non fixed term labor contract. If the laborer proposes or agrees to renew or conclude a labor contract, in addition to the laborer proposing to conclude a fixed term labor contract, under certain conditions, an open-ended labor contract shall also be concluded.
 Legal basis
 Article 14 of the Labor Contract Law, in any of the following circumstances, if a worker proposes or agrees to renew or conclude a labor contract, a non fixed term labor contract shall be concluded unless the worker proposes to conclude a fixed term labor contract:
 （1） The laborer has worked in the employing unit for ten consecutive years;
 （2） When the employer first implements the labor contract system or the state-owned enterprise restructures and re concludes the labor contract, the employee has worked in the employer for ten consecutive years and is less than ten years away from the statutory retirement age;
 （3） The labor contract is renewed after two consecutive fixed term labor contracts are concluded, and the laborer does not have the circumstances specified in Article 39 and Item 1 and Item 2 of Article 40 of this Law. If an employer fails to conclude a written labor contract with a worker at the end of one year from the date of employment, it shall be deemed that the employer has concluded a non fixed term labor contract with the worker.
 Legal basis
 Article 14 of the Labor Contract Law of the People's Republic of China (2012 Revision) [Non fixed term labor contract] Non fixed term labor contract refers to the labor contract with no fixed termination time agreed between the employer and the employee.
 An employer and a worker may conclude a non fixed term labor contract upon consensus. In any of the following circumstances, if the laborer proposes or agrees to renew or conclude a labor contract, an unfixed term labor contract shall be concluded unless the laborer proposes to conclude a fixed term labor contract:
 （1） The laborer has worked in the employing unit for ten consecutive years;
 （2） When the employer first implements the labor contract system or the state-owned enterprise restructures and re concludes the labor contract, the employee has worked in the employer for ten consecutive years and is less than ten years away from the statutory retirement age;
 （3） The labor contract is renewed after two consecutive fixed term labor contracts are concluded, and the laborer does not have the circumstances specified in Article 39 and Item 1 and Item 2 of Article 40 of this Law.
 If an employer fails to conclude a written labor contract with a worker at the end of one year from the date of employment, it shall be deemed that the employer has concluded a non fixed term labor contract with the worker.