In this paper, it takes the defense of "insider threat" as an entry point, the "data mining algorithms" as the key technology, the audit decision making and evaluation of internal control of meso information system as the research objective, in combination with the application environment of meso audit and information system audit, the model of internal control management of meso information system is constructed under the perspective of "insider threat", based on which, the internal control management of information system suitable for Chinese meso economy is to be established.