初中大班额班级指的是人数在56人以上的班级，在本人所在的云南省，大班额班级普遍存在。大班额班级中涌现了众多的非正式群体，这已经是不容忽视的现象。非正式群体对班级、班级内学生以及学校均有着不容忽视的影响。如何正确认识并引导初中大班额班级中的非正式群体是一个亟待解决的问题。本研究选取了云南省大理市X中学初二年级八年级全体学生以及其中的X班作为对象，采用调查问卷法、社会网络分析法以及半开放式访谈法，运用了SPSS软件以及UCINET.6软件对数据进行了处理，此外还对代表学生进行了访谈，对访谈记录进行了整理、译码和分析，针对初中生大班额班级中的非正式群体的特征类型以及影响进行了量化和质化结合研究、理论分析和探讨，得出以下结论： 1.大班额班级中的非正式群体有其鲜明的特征，主要有以下9个方面：①大班额班级中的非正式群体规模变化多，出现大群体中有小群体的嵌套现象；②非正式群体的凝聚性强，结构稳定；③不同非正式群体的民主程度有差异，由班级核心成员组成的非正式群体的民主程度比其他非正式群体的民主程度要高；④在班级和非正式群体中，均存在核心人物，他们对班级中的学生和整个班级的发展有巨大影响；⑤群体内部成员的亲密性高，男生群体的亲密性高于女生，不同群体间的独立性有差异，由班级的边缘学生组成的非正式群体基本不会与其他群体有联系；⑥群体间的交往频次低；⑦群体内具有自己的行为规范，群体内成员均会遵守；⑧非正式群体的形成原因多样，其中兴趣相同是个重要原因；⑨非正式群体的目标方向性较差，大部分群体没有明确的目标方向，除了由班级核心成员组成的群体外，其他群体的目标方向与班级的目标无关。 2.根据大班额班级中的非正式群体的特征，可以将非正式群体分为娱乐型群体、兴趣型群体、核心型群体、情感型群体和边缘型群体五种类型，每种类型均有自己的特点，其中以娱乐型群体和兴趣型群体居多。 3.大班额班级中的非正式群体对群体内成员以及整个班级均有积极影响和消极影响，对群体内的成员来说，积极影响多于消极影响；对于班级来说，是以积极影响为主还是消极影响为主很大程度上取决于班主任被学生所爱戴的程度，班主任受到爱戴的班级以积极影响为主，学生不认可班主任的班级以消极影响为主。 4.针对大班额班级的非正式群体的研究，管理者应当采取针对性措施对班级进行积极管理，促进班级的良性发展。主要措施有：①开展丰富多彩的班级活动；②充分发挥核心人物的积极影响；③积极改变边缘学生和孤立者；④建立民主的班级制度；⑤加强群体间联系；⑥充分发挥班主任的个人魅力。 本研究将帮助教育工作者，特别是班主任进一步认识大班额班级中的非正式群体，有效引导非正式群体发挥积极作用，对一线班主任展开教育教学工作有着重要意义。

The large class in junior middle schools refers to the class with more than 56 students. Many large classes are prevalent in Yunnan Province, where the author works. Many informal groups have emerged in large class, and this phenomenon cannot be ignored.Those informal groups have significant impacts on classes, students in classes, and schools.How to correctly understand and guide those informal groups in the large classes in junior high schools is a critical problem to be solved.This research selects all the students of Grade 8 and Class 337 of Zhengyang Campus of Xiaguan No. 4 Middle School in Dali City, Yunnan Province as the research objects, adopts the questionnaire method, social network analysis method, and semi-open interview method, and applies the SPSS software and UCINET.6 software to deal with the data. In addition, the representative students are interviewed; the interview records are sorted, decoded, and analyzed.Aiming at the characteristics and effects of the informal groups in large classes of junior high school students, this thesis makes a quantitative and qualitative research, and theoretical analysis & exploration. The conclusions are obtained as follows: 1. The informal groups in the large classes have their unique characteristics, which mainly include the following 9 aspects: ①There are various scales in the informal groups of the large classes; the nesting phenomenon occurs--small groups appear in large groups; ②The informal groups have strong cohesion with stable structures; ③The democracy degrees of different groups are different, and the democracy degrees of the core groups are higher than that of other groups. ④In classes and in informal groups, there are core figures, who have great influences on the development of the students and the whole class. ⑤The internal members have close relationships. The closeness of the male group is higher than that of the female group; the independence of different groups is different; the marginal groups have little association with other groups. ⑥The frequency of communication among groups is low; ⑦ The groups have their own behavior norms, whose members will abide by; ⑧ There are various reasons for the formation of informal groups, in which the same interest is an important reason; ⑨The orientation of the informal group is poor, and most groups have no clear goal direction. Except the core groups, the targets direction of other groups have nothing to do with the class goal. 2.According to the characteristics of the informal groups in large classes, the informal groups can be divided into five categories as follows: the recreational group, the interest group, the core group, the emotional group, and the marginal group, each of which has its own characteristics.Among them, the recreational groups and the interest groups are the majority. 3.The informal groups in the large classes have positive and negative influences on the members of the groups as well as the whole classes. For the members of the group, the positive influences are more than the negative influences; for the class, to a large extent, it depends on the degrees that the head teacher is loved by the students: for the class in which the class teacher is loved, the influences are mainly the positive influences; for the class in which the students are not in recognition of their head teacher, the influences are mainly the negative influences; 4. According to the research of the informal groups in large class, managers should take many targeted measures to actively manage the class and promote the positive development of the class. The main measures are as follows: ①carrying out abundant class activities; ② giving full play to the positive influence of the core figures; ③changing the marginal students and isolators actively; ④ establishing a democratic class system; ⑤ strengthening inter-group relations; ⑥ giving full play to the personal charm of the head teacher. This research will be helpful for educators, especially the head teachers of classes, to further understand the informal groups in large classes, and guide the informal groups to play active roles effectively. It is significant for the frontline head teachers to carry out the education and teaching work.