Background and Objective: Aggression is one of the most common problems among children who struggle with this behavioral problem during COVID-19 quarantine and negatively affects their quality of life. The aim of this study was to determine the effect of regular exercise on aggression and quality of life of students during coronavirus quarantine. Materials and Methods:The present study was a quasi-experimental study with a pretest-posttest design that was conducted in the academic year 2020-2021. The present study population consisted of girl students aged 10-12 years in Mahmoud Abad city of Mazandaran, of which 40 people were randomly divided into two groups of experimental (20 people) and control (20 people). Before and after the training sessions (12 sessions, three sessions per week for 45 minutes), the subjects completed the Aggression and Quality of Life Questionnaires. Independent-Samples T-Test and Paired-Samples T-Test statistical methods were used to analyze the data. Results: The results showed that there was a significant difference in research variables between the two groups after four weeks of regular training (P<0.05). Regular exercise in children caused a significant decrease in aggression score and a significant increase in quality of life score after exercise in the experimental group (P<0.05), but no significant difference was observed in the control group (P>0.05). Conclusion:The results showed the positive effect of online regular sports activity during the coronavirus quarantine, on increasing the quality of life and reducing the level of aggression of girl students. It is suggested that appropriate and attractive sports activities in all schools of the country be performed virtually in all educational levels on a regular basis.