Online shopping has progressed from having customers passively browse through product pages to having them proactively engage in communication dialogs with product sellers via Live-Chat. Customers indicated that communication with seller is an important type of salesperson service, which begins from their information search and ends with their purchase decision. Building on Content and Style (C&S) framework, this study seeks to understand how the intra-transaction communication influences the customers’ purchase behaviour in environment of e-commerce. By collecting 1234 communication sessions and their following purchase orders from 85 customers, we have a preliminary test of the proposed conceptual hypotheses, and results indicated that informativeness, conversation topic, and emotional expression had significant positive impact on the likelihood of customers’ purchase. This study presents a theoretical-driven and empirically validated proposition to improve the intra-communication to aid customers’ online shopping.