How to motivate patients to purchase paid online health platform is important to the profitability of a platform operator. Based on updated IS success model, this paper establishes a research model to investigate the effects of perceived platform quality (including platform service quality, information quality and system quality) and consultation service quality (including consultation service benefit and consultation service risk) on consumers' willingness to pay (WTP). Using SPSS and Smart PLS, we analyzed 409 data from an online health service platform in China. The results showed that perceived platform quality and consultation service benefit were positively correlated with consumers' WTP. Conversely, consultation service risk affected consumers' WTP negatively. Our study promotes the research from consumers' using intention to consumers' willingness to pay, as well as provides a guideline to help operators of online health platforms improve user payment rates.