OBJECTIVE: To investigate the relationship between asthma and COVID-19. METHODS: We searched the existing literature and researches to analyze the possible reasons. RESULTS: The possible reasons for the very low COVID-19 infection in asthma patients in China may be as follows: the expression of ACE2 in asthma patients is relatively low; the use of ICS in asthma patients may have protective effect; data bias and ethnic differences are also possible reasons, too. CONCLUSION: The relationship between asthma patients and COVID-19 has not been completely clear, which needs further study.