Objective: This study was conducted to describe the social, mental health difficulties and psychological behavior of students at some middle and high schools in Hanoi during the COVID-19 lockdown period. Methods: This is a cross-sectional study conducted in November 2021 using the form of an online survey on 5,315 students aged 11-17 years old residing in Hanoi. The four main outcome variables included family care and pressure, self-esteem, coping with stressful situations, and anxiety. Results: Results show that during the COVID-19 epidemic, about 11.6% of students experienced domestic family violence. Up to 43.5% of students assessed that they spent so much time using electronic devices that they did not have time to connect with their families. About 7.4% of students had severe anxiety symptoms, and 67.9% had mild or moderate symptoms. The participants also reported low coping skills and self-esteem during COVID social distancing. Conclusions: The COVID-19 pandemic, following school closures and distance learning, negatively impacted the psychological development of middle and high school students in Hanoi city. High schools should prioritize integrating coping strategies into their curricula and implement coping interventions to counter the harmful impact of stress on mental health. Future research should investigate the potential association between the duration of school closures and temporal changes in mental health symptoms.