In the context of the national “Internet+medical” grant strategy, Word-of-mouth(WOM), as an important force to promote medical services online - has not been given enough attention by theoretical researchers. What are the factors that would influence the online medical eWOM from Internet users to patients? Using experimental methods, this paper found that tie strength and percieved severity of the disease in?uence the WOM tendency, whilst gender moderates the effect. Data shows that people are more willing to spread positive eWOM to their strong ties or to severe patients. More importantly, the transmission patterns differ by gender-males are more willing to recommend to strong ties, whereas females do not show such preference. However, females tend to recommend more to patients with severe disease, yet there is no such difference among males. Moreover, the study also found that individuals with high interdepend self are more likely to pass on eWOM; the higher the product's familiarity and the lower the perceived risk would strengthen the willingness of WOM engagement.