The principle of “leniency to those who plead guilty and accept punishment” originates from the criminal policies of “leniency to those who confess their crimes and severity to those who refuse to” and “tempering justice with mercy”. It is the further development of the leniency aspect of these policies under new historical conditions. Although this principle has already been reflected in the Chinese Criminal Law and Criminal Procedure Law, there is still room for further improvement. In the future, China may consider providing for this principle in the Criminal Law and integrate the relevant provisions in the current laws and judicial interpretations, and impose necessary restrictions on the extent of leniency. In criminal proceedings, the summary procedure can be applied in cases where the defendant pleads guilty and accepts punishment. The legitimacy of the summary procedure comes from the voluntary waiver of formal trial by the defendant. It needs to be supported by the voluntariness, authenticity and sensibility of the defendant’s decision to plead guilty and accept punishment. China should construct a procedural diversion mechanism by taking the plead of guilty and acceptance of punishment by the accused as the precondition and strengthen the function of procedural diversion through the application of the doctrine of prosecuting discretion at the pre-trial stage; at the trial stage, a pluralistic summary procedure should be constructed in light of the seriousness of the circumstance and the degree of difficulty of the case. In the discussion of the system of “leniency to those plead guilty and accept punishment”, there should be less utilitarianism and more rational analysis. The respect of judicial principles should be taken as the primary principle of the reform; and the bottom-line requirements of the rule of law should be adhered to in the process of turning policies into legislation or turning legislation into policies.