This prospective observational study examined changing trends of excess self-protective behavior (EPB), and their association with perceived risk, perceived severity, and irrational beliefs about prevention during the Chinese COVID-19 epidemic. Participants were recruited for an online panel survey. There are 150 participants for the baseline and 102 for the final survey. There were 5 waves of interviews. Perceptions of risk and disease severity were measured by single items. Irrational beliefs about prevention and EPB comprised 5 common prevention misconceptions. Descriptive statistics and the CATMOD program were used for data analysis. The prevalence of participants perceiving personal risk of contracting COVID-19 and severe consequences of the disease was 18.6% and 25.5%, respectively, at baseline, and declining to 4.9% and 17.6% at final observation. The 5 selected EPB also showed a diminishing trend. Belief in COVID-19 prevention myths trended upwards. Perceived risk was positively associated with each EPB, and perceived severity with disinfection of clothes and hoarding of products. Myth adherence was positively associated with disinfection of clothes and both hand washing and sanitization. This study yields new information about EPB among the Chinese public. Policy modifications and public education interventions are essential for minimizing the adverse health effects of subscribing to irrational beliefs.