昆山“反杀案”引发了社会对正当防卫制度的关注，该案折射出的正当防卫的认定难题也引起了刑法界的激烈争论。我国法律对正当防卫做出了规定，但在多年司法实践中正当防卫认定过于严苛，尤其是昆山案中使用的无限防卫权。因此笔者以昆山“反杀案”为切入点，结合近年来同类型的案件，为论点提供支撑，对我国正当防卫制度进行论述，对正当防卫的认定困难进行分析并对此提出建议，以期更好地发挥正当防卫制度支持正义、鼓励人民同不法侵害做斗争、引导社会良好风气的形成、维持社会安全与稳定的作用。

The Kunshan case had aroused the society's concern on the justifiable defense system, whose identification reflected in the case had also caused heated debate in the criminal law community. China's law had made provisions for proper defense, but in the years of judicial practice, legitimate defense no longer worked, especially the unlimited defense rights used in the Kunshan case. Therefore, I will take the Kunshan case as the entry point and combines the same type of case in recent years to provide support for the arguments. I will discuss the legitimate defense system in China, and analyze the difficulties in identifying difficulties, to give full play to the legitimate defense system to support justice, encourage people to fight against illegal infringement, and guide the good atmosphere of society. The formation and maintenance of social security and stability will be promoted.