AbstractSocial distancing is an effective measure to prevent epidemic infections during a pandemic outbreak, but its psychological value in COVID-19 pandemic mitigation remained less detected. Our study fills this gap by conducting a nationwide survey in China between 12 and 25 February (2020), and a follow-up survey targeting the same participants between 25 and 28 March (2020). We have discovered that perceived increased time staying at home, a subjective agency for social distancing, positively predicts not only risk perception of COVID-19 epidemic at the outbreak and eased stage, but also predicts subjective controllability of COVID-19 epidemic at the eased stage. Given that risk perception indicates potential active engagement of preventative behavior and that subjective controllability associating with self-efficacy could promote individual health behavior, this study preliminarily justifies the value of social distancing from the angle of perceptual factors, adding to existing mounting evidence of its effect on physically controlling pandemic spread.