All the preconditions of the system of confession, confession and leniency of punishment lie in confession, and the dual attributes of the entity and procedure of confession and the multiple factors that affect the confession determine the difficult complexity of the confession process. As the first criminal procedure to contact with the guilty plea - investigation and interrogation, the first contact with the suspect and listen to his plea or confession. If the confession of the suspect is fixed as legal and effective evidence at this stage, not only will the truth of the case be found as soon as possible, reduce or even recover the consequences of criminal harm, but also the true confession will help the smooth implementation of the leniency system of guilty plea and punishment, in order to save judicial resources, achieve crime management and resolve social conflicts. Taking the judicial documents from 2021 to 2022 as the analysis sample, this paper discusses the basic structure framework of “confession”, the influencing factors of “confession” voluntariness, and the review method of “confession”, and strives to supplement and improve on the basis of the research of predecessors, so as to further promote the development of the leniency system of confession and punishment in China.