There is a legal limit on probation periods, wages must be at least 80% of the regular rate, and only one probation period may be set per employee

Cost: Zero expense. Spend a few minutes before signing to verify that the contract’s stated term and probation length match the legal requirements.
In plain terms: For contracts lasting up to one year, the maximum probation period is one month. For contracts from one to three years, it is two months. For contracts exceeding three years, or open‑ended contracts, the maximum is six months. An employer may only place an employee on probation once; offering a second probation period after the employee has been regularized is illegal. During probation, wages must be no lower than the minimum wage for that position or 80% of the agreed regular wage, and they must also meet the local minimum wage standard.
Benefit: Under the law, contracts of more than three months but under one year may have a probation period of no more than one month; those from one to three years may have a maximum of two months; and contracts of three years or longer, as well as open‑ended contracts, may have a maximum of six months. Contracts with a term defined solely by completion of a specific task, or those lasting less than three months, may not include any probation period at all. An employer may stipulate only one probation period for any given employee. If a contract mentions a probation period but does not specify its length, that period is deemed invalid and the entire contract term applies. Probation wages must be at least 80% of the lowest comparable wage within the organization or 80% of the agreed regular wage, and they must also meet the local minimum wage. Should an employer set a probation period longer than permitted by law, it must compensate the employee for the excess time at the regular monthly wage rate. Termination during probation is only permissible under specific legal circumstances, and the employer must provide a valid reason to the employee (nationwide).
Evidence grade: A
Sources:全国人大常委会 (2007). 劳动合同法（第十九、二十、二十一、八十三条）. http://www.gov.cn/gongbao/content/2007/content_711013.htm
Notes: Three common violations occur frequently. First, a one‑year contract may contain a three‑month probation period. Second, after an employee becomes regular, the employer may attempt to impose another probation period. Third, some employers claim “no social insurance during probation,” yet the obligation to enroll begins on the first day of work, regardless of probation status; details are provided in Section 12, Item 16. Being dismissed during probation does not mean no compensation; eligibility depends on whether the dismissal meets legal criteria. Unlawful termination entitles the employee to double the regular wage as stipulated in Item 6.