At present, many countries and regions are strengthening the construction of digital cities, expecting to obtain valuable intelligence from big data by means of information technology, and the massive accumulated security video and alarm information can be analyzed to discover the laws of the data and form correlated data to provide reference for police work. In this paper, from the actual needs of intelligence analysis, cloud computing and big data technology is used to design a cloud data(CD) intelligence investigation system(IIS) to meet the requirements of information development, by building an intelligence information center, using decision tree algorithm(DTA) to analyze and classify massive data, solve the problem of insufficient human resources for on-site investigation, effectively improve the efficiency of investigation and crime solving, and provide technical support for the construction of a harmonious and stable social environment.