The past eight months witnessed COVID-19's fast-spreading at the global level. Limited by medical resources shortage and uneven facilities distribution, online help-seeking becomes an essential approach to cope with public health emergencies for many ordinaries. This study explored the driving forces behind the retransmission of online help-seeking posts. We built an analytical framework that emphasized content characteristics, including information completeness, proximity, support seeking type, disease severity, and emotion. Adopting the framework, a quantitative content analysis was conducted with a probability sample of 727 posts. The results illustrate the importance of individual information completeness, high proximity, instrumental support seeking. This study also reveals the severity principle and the power of anger in the dissemination of help-seeking messages. As one of the first online help-seeking diffusion analyses in the COVID-19 period, the theoretical and practical implications of this study are further discussed.