中华人民共和国工会法 第十一条 (2022年1月1日起施行)

用人单位有会员二十五人以上的，应当建立基层工会委员会；不足二十五人的，可以单独建立基层工会委员会，也可以由两个以上单位的会员联合建立基层工会委员会，也可以选举组织员一人，组织会员开展活动。

The Trade Union Law of the People's Republic of China, Article 11 (effective since January 1, 2022) 

The trade union of an employing unit with 25 or more members should establish a primary trade union committee. If members number less than 25, a primary trade union committee may be established independently, or a primary trade union committee may be jointly established by members of two or more units, or an organizer may be elected to organize members to carry out activities.