Based on employees and employer matching data in 2012, the paper attempts to analyze effect of wage distribution of Chinese trade union by adopting the method of unconditional quantile regression. The results show that under the unions covering effect, the pay gap between the union enterprises workers and non-union enterprises workers presents “stick-floor effect”; under the union members effect, the pay gap between union members and non-union members presents “stick-floor effect”; characteristic differences is obviously different under the unions covering effect and the union members effect; the union enterprises have more advantages to eliminate the gender wage discrimination of middle-income workers. At last, two policy recommendations are put forward according to the conclusions of the research.