The view on the functions of the trade union is an important component of the Marxist trade union theory and is a crucial dimension for understanding the political forms and operational mechanisms of modern trade unions organizations. In the process of leading workers' movement and conducting theoretical critiques on capitalist political economics, Marx and Engels provided a theoretical exposition on the functions and limitations of the trade union. They recognized the signifi cant roles of trade unions in safeguarding workers' wage interests, promoting political mobilization, providing social relief, and instilling class consciousness. However, they also noted that under the capitalist wage labor system, the trade union could be potentially absorbed by capitalist ideology and the bourgeois "appeasement policy", which might lead to a position antagonistic to the working class. To address these emerging tendencies, Marx and Engels emphasized that trade unions must adhere to the leadership of the proletarian vanguard party. The strong leadership of the proletarian vanguard party is essential to ensure the purity and progressiveness of the trade union organizations. This important principle serves as the theoretical source and ideological foundation for the Chinese trade unions' necessity to uphold the leadership of the Communist Party of China.