Due to the increasing popularity of social media, social commerce has been emerging as a new form of e-commerce. As a driving force of the popularity and growth of social commerce, electronic wordof-mouth (eWOM) plays an important role during the process of consumers’ purchase decision making in social commerce. There are adequate studies that have offered a broad view on what makes the helpfulness perception of eWOM. However, little research has investigated the effect of argument strength and source dynamism of eWOM. Drawing on Stimulus–Organism–Response (S–O–R) model and Elaboration Likelihood Model (ELM), an integrated research model is proposed and tries to explore the impact of argument strength and source dynamism of eWOM on consumers’ affective response and cognitive response and how do they affect the formation of consumers’ purchasing intention. We expect that our study can make a contribution to theoretical development and provide some guidance for retailers to carry out a better management strategy of eWOM.