Chinese system of evidence classification consists of the evidence classification provided by law . Compared with the western countries ruled by law,Chinese system of evidence classification has two distinctive characteristics:a special article of law is used to make a clear and definite list of evidence category and some peculiar categories of evidence are provided .Thought the view that there are some serious defects of logic in Chinese system of evidence classification has already become the consensus of the academic field of procedure law,the major elements of this system are still remained in legislation .The causes of this phenomenon must be found out from the perspective of the function of the system . The academic world generally thinks that it is the legal function of Chinese system of evidence classification to limit the admissibility of evidence . That means,according to the provisions for the legal forms of evidence,any evidence materials that do not belong to the legal categories of evidence will be inadmissible and must be excluded from the scope of evidence during the criminal procedure .However,this academic opinion is only an imaginable function of the system of evidence classification .The function of limiting the admissibility of evidence has never been realized in the practice of Chinese criminal procedure .It has hardly happened that some materials which have probative value were excluded just because of their forms not belonging to the legal forms of evidence .One reason for this is that,though Chinese law has provided the categories of evidence,the corresponding admissibility rules of evidence have not been established by law at the same time .Another reason is that the evidence categories provided by law can be interpreted to cover all forms of evidence . From the macroscopic perspective of legal background,Chinese system of evidence classification is coeval with the investigation-oriented doctrine and the trial mode of relying investigation files,which have existed in Chinese criminal justice for a long time .There are two obvious tendencies of applying evidence against this background:cognizing the evidence from the perspective of investigative subject rather than trial subject and presenting the evidence in written form .Through setting up a set of evidence categories that correspond to the investigative actions and confusing the investigative subject and the trial subject while interpreting the evidence categories,Chinese system of evidence classification provides a legal approach to applying the evidence materials in writing .And then,it caters for the above-mentioned requirements of the investigation-oriented doctrine and the trial mode of relying investigation files .As a result,the actual function of Chinese system of evidence classification is changed from limiting the admissibility of evidence to enhancing the admissibility of investigation files . This is very disadvantageous to improving criminal proceedings and establishing the rules of evidence in China . In order to realize the due function of Chinese system of evidence classification,which is to limit the admissibility of evidence and exclude the inadmissible evidence,evidence categories must be reasonably set up and a variety of admissibility rules of evidence must be established and improved according to the requirements of trial-oriented doctrine . At present,limiting the admissibility of investigation files would be the main approach to changing the function of this system .The concrete measures include defining the evidence categories from the perspective of trial so as to provide a theoretical basis of limiting the admissibility of investigation files,gradually restricting and reducing the use of investigation files in criminal trial through the method of judicial interpretation .