Coronavirus disease (COVID-19) is currently a world-wide major public health event. Since study sites of clinical trials are primarily at healthcare institutions and investigators are primarily clinicians, the epidemic inevitably has a huge impact on a large number of ongoing clinical trials. The proper implementation of clinical trials in key aspects and the quality of core data collection will greatly influence the validity of the final results. In this paper, we analyzed the potential impact of the outbreak of a new epidemic infectious diseases on the clinical trials from seven aspects, which involves the selection of study participants, randomization, blinding, implementation of intervention measures, follow-up of primary outcomes, safety monitoring and project management. Corresponding countermeasures were put forward.