As an emerging charity model, critical illness network crowdfunding provides a source of funds for some critically ill patients in China who have difficulty paying their high treatment costs by themselves. This study aims to investigate the influencing factors of the public's willingness to donate to critical illness crowdfunding projects on Internet platforms. From a perspective combining the technology acceptance model and the theory of planned behavior, a complex and comprehensive structural equation model is proposed. We randomly selected 1,000 members of the public in China and empirically verified the study framework through structural equation modeling (SEM) based on 710 valid questionnaires. The results show that the public's donation willingness and the social distance to a critical illness crowdfunding project on an online platform positively affect the public’s donation behavior, and donation attitude positively affect donation willingness; perceived usefulness and empathic concern positively affect the public’s donation attitude, which in turn affects its donation willingness.