In order to explore how Web search volume dynamically influences product sales during the whole product life cycle, this paper collects Web search volume and sales data of movies and does an empirical analysis using econometric models. The empirical results show that Web search volume before the launch of a new product has a positive impact on the product sales in the initial period of introduction stage. During the whole product life cycle, Web search volume has a positive and significant impact on product sales, but the impact declines gradually across the life cycle. The impact of Web search volume on sales is larger in the early stage of the product life cycle than in the late stage of the product life cycle.