China has long been suffering from the problem of having health care that is expensive and difficult to access. Online patient-provider communication (OPPC) can offer a viable channel to increase access to care. However, through what underlying mechanisms OPPC can be associated with better health outcome is under-researched. To fill this research gap, this study investigated OPPC usage in China and identified psychological processes linking OPPC to emotional well-being. With two-wave panel surveys conducted in China, we found that mobile health app, social media, and health information service website were three common platforms for OPPC, followed by patient portal, whereas e-mail was used least frequently. Overall, OPPC did not have any direct effect on emotional well-being. Instead, OPPC first increased users' perceived social presence of providers in OPPC, which in turn triggered sense of patient empowerment, which finally enhanced emotional well-being.