Objective: To explore the association between acute stress response during the outbreak of COVID 19 and peer bullying behaviors during the normalized management of COVID 19 among middle school students, and to provide a basis for developing relevant measures for peer bullying prevention. Methods: In December 2020, a total of 2 219 students from two junior middle schools in South Anhui(Xuancheng City) and North Anhui(Huaibei City), were selected to participate in this study by using the cluster sampling method. The occurrence of verbal bullying, relational bullying, physical bullying and cyberbullying behaviors among victims and perpetrators of bullying, and self rated acute stress response during the outbreak of COVID 19 (social isolation) were investigated. Multiple Logistic regression models were conducted to explore the relationship between different levels of acute stress response during the COVID 19 outbreak and peer bullying behaviors among middle school students. Results: The reported rate of peer bullying, being bullied by others and bullying others during the COVID19 normalized management were 65.8%, 63.8% and 27.1%, respectively. The reporting rate of verbal bullying victimization was the highest (54.8%) and cyberbullying others was the lowest (4.6%). The mean score of acute stress response among middle school students during the COVID 19 outbreak was (6.50±1.67). Except for physically bullying others, the reported rate of other bullying behaviors was the highest in the high level acute stress response group ( P <0.05). Multiple Logistic regression models showed that high levels of acute stress response were associated with high risk of verbal bullying victimization ( OR =1.38), relational bullying victimization ( OR =2.28), physical bullying victimization ( OR =1.87) and cyberbullying victimization ( OR =2.30) after adjusting for related confounders. In the high level acute stress response group, verbal bullying ( OR =1.80), relational bullying ( OR =1.99), physical bullying ( OR =1.76) and cyberbullying ( OR =2.32) had higher risks of bullying others than in the low level acute stress response group ( P <0.05). Conclusion High levels of acute stress response are associated with different peer bullying behaviors, with stronger associations with cyberbullying.