Legal analysis: illegal. Post adjustment and salary reduction belong to the change of labor contract and need to be negotiated with the workers. Unless the company and the employee agree in the labor contract in advance that the company can unilaterally adjust the position of the employee, in other cases, it is usually necessary to negotiate with the employee before adjusting the position.
Legal basis: Article 35 of the Labor Contract Law of People's Republic of China (PRC), the employer and the employee can change the contents of the labor contract through consultation. Changes to the labor contract shall be made in written form. The revised text of the labor contract shall be held by the employer and the employee respectively.