Based on the two-dimensional classification of quality assurance mechanisms, this study capitalizes on an adjustment event of quality disclosure strategy on Ctrip.com in June 2017, and uses the sales data of online outbound package tour products to investigate the impact of transparency of quality disclosure on sales, as well as its moderating effect on the relationship between eWOM valence and sales. We uncover following interesting findings as follows. First, the valence of eWOM has a curvilinear (inverted U-shaped) relationship with sales. Second, the transparency of quality disclosure has a positive moderating effect. Our study reveals how the information transparency strategy influence the development of the platform ecosystem.