我国现行《刑法》第20条在对正当防卫作规定的同时也规定防卫过当行为应当负刑事责任。但刑法并没有对“明显超过必要限度”作出界定,这造成在司法实践中认定防卫过当行为的偏差,也引起了罪与非罪的争议。本文从防卫手段与防卫限度之合法性的关系作出分析;指出了“明显超过必要限度”造成重大损害的伤害程度应当为重伤以上。 Article 20 of the existing “Criminal Law” in our country stipulates that due diligence also stipulates that acts of defensive conduct should be criminalized. However, the criminal law did not define “apparently exceeding the necessary limit ”, which led to the deviation of defensive over behavior in judicial practice, and also caused the controversy between sin and non-sin. This article analyzes the relationship between the means of defense and the legitimacy of defense limits, and points out that the degree of injury that caused “significant damage” should be seriously injured if it is “obviously exceeding the necessary limit”.