Background: The World Health Organization characterized the Coronavirus disease 2019 (COVID-19) as a pandemic on March 11th. Many clinical trials on COVID-19 have been registered, and we aim to review the study characteristics and provide guidance for future trials to avoid duplicated effort. Methods: Studies on COVID-19 registered before March 3rd, 2020 on eight registry platforms worldwide were searched and the data of design, participants, interventions, and outcomes were extracted and analyzed. Results: Three hundred and ninety-three studies were identified and 380 (96.7%) were from mainland China, while 3 in Japan, 3 in France, 2 in the US, and 3 were international collaborative studies. Two hundred and sixty-six (67.7%) aimed at therapeutic effect, others were for prevention, diagnosis, prognosis, etc. Two hundred and two studies (51.4%) were randomized controlled trials. Two third of therapeutic studies tested Western medicines including antiviral drugs (17.7%), stem cell and cord blood therapy (10.2%), chloroquine and derivatives (8.3%), 16 (6.0%) on Chinese medicines, and 73 (27.4%) on integrated therapy of Western and Chinese medicines. Thirty-one studies among 266 therapeutic studies (11.7%) used mortality as primary outcome, while the most designed secondary outcomes were symptoms and signs (47.0%). Half of the studies (45.5%) had not started recruiting till March 3rd. Conclusion: Inappropriate outcome setting, delayed recruitment and insufficient numbers of new cases in China implied many studies may fail to complete. Strategies and protocols of the studies with robust and rapid data sharing are warranted for emergency public health events, helping the timely evidence-based decision-making.