The particularities of Chinese union practices in the private sector and their impacts on the labor relations climate have raised much controversy. This paper presents the findings of a study that analyzed data from 926 enterprises in Chongqing, China, through the lens of institutional trust. The study was designed to examine the influence of union practices on the labor relations climate at the enterprise level. Particular attention was paid to the possible moderator effect that both employee and management trust in unions had on the labor relations climate. We found that employee–union trust positively moderated the impact of union practice on the labor relations climate. However, if management–union trust exceeded employee–union trust, management–union trust weakened the moderator effect of employee–union trust. In other words, management–union trust negatively moderated employee–union trust. This article is organized as follows. In section “Introduction,” we introduce the institutions Chinese unions operate in, especially regarding disputes over the effects on the labor relations climate. In section ‘Theory and hypotheses,” we review the literature and develop the hypotheses. In section “Materials and methods”, we describe the data and method, and in section “Results,” we present the results of the model. Finally, in section “Discussion,” we discuss the implications for China’s union development and note the limitations of the study.