Legal analysis: the employer has no right to detain the employee's health certificate, which is illegal. When employing workers, the employing unit shall not detain the workers' resident identity cards and other documents, and shall not require the workers to provide guarantees or collect property from them in other names. It is illegal for the employer to detain the employee's health certificate, and it can complain to the labor inspection brigade.
Legal basis: Article 9 of the Labor Contract Law of People's Republic of China (PRC), the employing unit shall not detain the employee's resident identity card and other documents, and shall not require the employee to provide guarantee or collect property from the employee in other names.