In recent year, the rapid development of e-commerce has provided consumers with a new channel to purchase products and services online and also make lots of business moving to online marketplace. However, regarding the online bookstore customers' purchasing intention, there are obvious lack of solid guidelines to show how online bookstore users' demand affect consumer purchase intention. Hence, exploring whether there are some connection between the purchase intention of users and the demands of human to be satisfied or not is valuable. The objective of this study is to understand the relationship between the demand and purchase intention of the online bookstore users. Also, find out the moderating effect caused by demographic variable. A total of 327 copies were returned by using purposive sampling. The consequence surveys that the purchase intention of online bookstore users has positive relationship with their self-growing and socializing demands. Also, the demographic variable such as gender plays a role that moderates the relationship between demands and purchase intention exactly. According to the results, a number of suggestions are given to academics and practitioners.