Objective: To establish a multilevel structural equation model (MSEM) to investigate the influence of the class atmosphere and deviant peer affiliation on bullying at both the coup and individual levels. Methods: A total of 1422 junior hi h school students were selected from 39 classes in Hainan, China. The class atmosphere scale, peer relations-bully scale and deviant peer affiliation questionnaire were issued. We conducted the common method bias test and correlation analysis, and the 1-1-1 model and 2-1-1 model based on MSEM. The hierarchical regression approach and Markov Chain Monte Carlo (MCMC) were used to test the reliability of the model. Results: (1) The class atmosphere negatively predicted bullying behaviour at both the class level and the individual level, and individual association with deviant peers played a partial mediating role between class atmosphere and bullying behaviour; (2)The impact of class atmosphere on bullying behaviour was more explanatory at the class level than at the individual level; (3)Compared to the individual levels, the class level was closer to the occurrence of bullying behaviour in class. Conclusion: This study identifies a nuanced relationship between class atmosphere and bullying behaviour, influenced by individual tendencies and coup characteristics related to deviant peer affiliations. We found that a good class atmosphere has an inhibitory effect on bullying behaviour: it suppresses bullying behaviour by preventing students from forming deviant peer affiliations. Anion these, the class level factors have greater impacts and better predictive effects on bullying behaviour. Practically, the study highlights the importance of educators to monitor adolescents’ friendship choices, promote healthy peer relationships, and foster an improved class atmosphere.

目的：探索班级氛围、结交越轨同伴与欺凌行为之间在学生层面及班级层面的关系。方法：采用班级氛围量表、欺凌行为量表及越轨同伴交往问卷，以班级为单位在海南地区6所初中的39个班级中对1422名初中学生开展问卷调查。结果：（1）班级氛围在学生层面及班级层面都对欺凌行为有显著的负向作用，且结交越轨同伴均起到部分中介作用；（2）低层级中介模型分析结果显示，班级氛围对欺凌行为的影响在班级层面比学生层面的解释力更高；（3）跨层级中介模型的拟合水平显著优于低层级中介模型，指示实际的班级氛围对于欺凌行为的预测更接近班级中的实际情况。结论：良好的班级氛围从学生层面和班级层面同时对欺凌行为起到抑制作用，并且通过抑制学生结交越轨同伴来抑制欺凌行为，其中班级层面因素对欺凌行为产生的影响效果更大且预测效果更好。