The police defense power is an important component of the polices responsibilities, its nature in the criminal law should be defined as the statutory performance that obstructs the illegal acts and excludes the criminal acts, which is obviously different from the similar defense in appearance. When implementing such defence power as a kind of administrative authority, police should abide by the that of ultima ratio, that of strict proportion and that of avoiding damage, prudently follow such rules as the condition for the cause of defense, the condition for the object of defense, the precondition for the defense, the condition for the limit of defence, and be carefully ware of improper defensive behavior, so as to realize the balance between public interests and personal rights. If the misusing of the police defence power is in conformity with the Tatbestand of the corresponding crime stipulated in the criminal law, the police should bear the corresponding criminal responsibility and be sentenced penalty according to law.