The success of social commerce depends on the actual transactions of consumers, which will be prevented in the presence of high uncertainty. However, attention paid to the uncertainty reduction strategies in social commerce is limited, especially from a unified theoretical framework. Based on uncertainty reduction theory (URT), this paper aims to investigate how three uncertainty reduction strategies (i.e. situational normality, perceived effectiveness of social commerce institutional mechanisms (PESIM) and swift guanxi) affect perceived uncertainty in social commerce, which in turn affects buyers' purchase intention and purchase behavior. The moderating effects of PESIM on the relationships between the other two strategies and perceived uncertainty were also tested.

In this study longitudinal data from 211 buyers who have usage experience of Xiaohongshu were collected to test the proposed model and hypotheses.

Results show that the three uncertainty reduction strategies significantly reduce perceived uncertainty. PESIM negatively moderates the relationships between situational normality and perceived uncertainty, swift guanxi and perceived uncertainty. Perceived uncertainty is negatively related to purchase intention. Purchase intention positively affects purchase behavior.

This study focuses on the role of uncertainty reduction mechanisms in promoting purchase behavior through uncertainty reduction and sheds light on the relationships among situational normality, PESIM, swift guanxi and perceived uncertainty based on URT, which have not been extensively studied from a theoretical perspective in social commerce contexts. Besides, this study investigates the moderating role of PESIM, which improves the understanding of the role of swift guanxi and situational normality in reducing perceived uncertainty under the boundary condition of PESIM.