Public health events are sudden, public in nature and have serious social hazards. The COVID-19 outbreak coincided with the Lunar New Year, which had a direct or indirect impact on all areas of society. Previous studies related to emergencies have found that a considerable number of college students lacked experience in dealing with emergencies, were not emotionally stable enough, lacked analysis and decision-making ability, were easily suggestible and acted more impulsively. Therefore, in this paper, based on the existing actual information, combined with the awareness and understanding of college students’ mental health, and based on the existing research results, the Hopfield-mental health model is used as a theoretical basis to study the trend of changes in college students’ mental health. The results of the study show that 83.21% of the people are more concerned about the situation of this new crown pneumonia epidemic and they think that the new crown epidemic has seriously affected their living habits; 65.45% thought that this new crown pneumonia epidemic did not have any major impact on their school life. The five sources of psychological stress, including academic, employment, economic, interpersonal relationship and love, were calculated and analysed in the model, which showed that employment stress, academic stress and economic stress were the largest sources of psychological stress among college students in this new pneumonia epidemic, accounting for 89%, 81% and 93%, respectively. They were followed by interpersonal and romantic stress, with 31% and 52%, respectively.