Abstract: Analyzing the data of previous surveys of Chinese private enterprises spanning 20 years, it is found that the proportion of labor union organizations in Chinese private enterprises has increased in the past 20 years, but declined slightly in recent years, but still accounts for half of the total. Based on the data of the tenth survey of private enterprises, the research shows that the factors influencing the formation of labor unions in private enterprises include not only the characteristics of enterprises, such as the time of registration, the types of registration, location, number of employed workers, net profit of enterprises, etc. It also includes the experience of private entrepreneurs in the system, political embeddedness, membership of the Federation of Industry and Commerce, etc. The closer the private enterprises or entrepreneurs are to the state, the more likely they are to establish labor union organizations in enterprises. In the aspect of employee wages and bonuses in private enterprises, after controlling many other possible factors, the study points out that the formation of labor unions has significantly improved the treatment of employees, and further analysis with quantile regression shows that the consequences are heterogeneous, that is, for enterprises with low employee treatment, labor union organizations have stronger positive effects. The above findings can provide an empirical basis for the formulation and evaluation of relevant policies, help to play the role of labor unions and promote the construction of harmonious labor relations in private enterprises.