Abstract:The paper attempts to analyze Chinese trade unions’ coverage effect on the wage gap by adopting the method of Blinder-Oaxaca, based on employees and employer matching data in 2012. The results show that: under the unions covering effect, the average wage gap between union and nonunion enterprises is not obvious; the union and nonunion enterprises salary differences mainly due to the characteristic difference of labor; unions fail to significantly affect the wage gap through human capital; unions affect the wage gap through the labor contract and collective contract; unions can reduce the gender wage discrimination.