It is common to see merchants reply to customer reviews in online malls. While extant research generally investigates the effects of merchants’ replies to negative reviews, the role of positive reviews remains a rather neglected factor in extant studies. In order to better reflect the real conditions in online malls, this study examines the role of positive reviews in the context of merchants’ online review response in two aspects. Firstly, we examine whether responding to positive reviews influences merchants’ sales by using the panel data collected from taobao.com. Secondly, little attention has been paid to whether the exhibition of positive reviews influences the effectiveness of merchants’ responses to negative reviews. Our study extends extant studies by introducing the moderating effect of the percentage of positive reviews. The exhibition of positive reviews is closely related to the generation of positive word-of-mouth and a high percentage of positive reviews can improve customers’ perceived credibility of the merchant. Therefore, if merchants gain a high degree of consumers’ trust, their responses are generally more effective and influence the sales more significantly.