The transition to Socialist-oriented market economy system caused a big change not only in labour market but also in labour relations. Labour relations between State and labourer in state owned enterprises shifted to employment relations between employer and employee with the legalization of private sector including domestic private enterprises and foreign invested enterprises(FIEs). Needly to say, the conflicts of legal rights and interests between employers and employees inevitably have caused labour disputes and strikes. Above all, Vietnam Constitution and Labour code provide Vietnamese employees a right to strike which is one of labour`s three primary rights. But strikes should be recognized as legal means to pressure employers in course of collective bargaining. Between 1995 and 2011 in Vietnam there had been 4,142 recorded strikes, and there was no legal strikes. 75.4% of strikes have happened especially in FIEs from Taiwan, Korea and Japan. The reasons that two-thirds of strikes occurred in FIEs can be explained by some causes. The main cause of strikes lies in the failure of the labour union at enterprise level effectively to represent the rights and interest of employees. Labour union at enterprise level needs to play a role not only in representing the legal rights and interests of employees but also in regulating conflicts and mediating between employers and employees. By strengthening these roles, a massive of wild strikes can be prevented effectively and be settle easily with a labour union at enterprise level.