Background: Since December 2019, 2019 novel corona virus (2019-nCov) disease (COVID-19) has extended to most parts of China with more than 80 thousand cases. From Feb 1 ^st to Mar 31 ^st of 2020, all children were asked to stay indoors in China. Then how it affected allergic asthma (AA) sensitized to house dust mites (HDM) in children was interestingly to clarify. Objective: To investigate the changes of clinical characteristics of children with AA sensitized to HDM during COVID-19 pandemic. Method: The data including asthma symptom scores(SS), visual analog scores (VAS), asthma quality of life questionnaire (AQLQ) and medicine scores (MS) as well as respiratory infections, cares, staying up late and diets, collected from children with AA sensitized to HDM from Feb 1 ^st to Mar 31 ^st of 2019 and 2020 retrospectively, were analyzed. Results: There were 85 children with AA sensitized to HDM included in this research. Compared with SS, VAS, AQLQ and MS of the patients from Feb 1 ^st to Mar 31 ^st of 2019, SS, VAS, AQLQ and MS of the patients improved significantly (p<0.05) during COVID-19 pandemic. No respiratory infections occurred among them and they got better cares, had better diets and stayed up late less during COVID-19 pandemic. Conclusion: During COVID-19 pandemic, children with AA sensitized to HDM got better health for staying indoors, which might be associated with no respiratory infections, better cares, better diets and less staying up late.