Abstract: Applying western theory to research problems in China is helpful to strengthen the Chinese and foreign academic exchanges and to solve practical problems. But because of geographical，cultural and traditional differences，localization of foreign theory is the important premise. At present，in the context of that domestic mass incidents occur frequently，Lewis Coser’s social conflict theory must be analyzed when being introduced into China’s practice. It is necessary to recognize the positive features: excessive assumptions，overmuch emphasis on the power，non-perfect of the theoretical system and some propositions beneath less biased. The multi-dimensional analysis of the causes of conflict，the dipartition of conflict types，the alerts of breakthrough conflict’s bottom line are very important and helpful. The mass incidents have dual function of positive and negative，such as avoiding social conflicts，smoothing channels for expressing public opinion，promoting social system change and producing social security cases，forming negative demonstration effect，cumulating negative social psychology. So，we must remove the negative function of social conflicts and strengthen the positive guidance in promoting institutional management，grasping the focus of conflict and taking all types of measure.

Key words: Lewis Coser, social conflict theory, social function, mass incidents, localization