Despite researcher’s attempts on examining knowledge sharing behavior, the impact of purchasing behavior on sales of knowledge products remains largely unknown in the existing literature. To fill this void, using the data collected from Zhihu.com, we develop a two-phase framework to assess the impact of factors of live (i.e., price), factors of other audiences (i.e., review scores) and factors of speaker (i.e., reputation) on sales. Moreover, with start date of a live as a dividing point, our study examines the difference of impact of these factors on sales between two sales stages (before a live start VS. after a live starts). Results and implications are analyzed and discussed.