ORA(Organizational Risk Analyzer) is a dynamic network evaluation and analysis tools which developed by the center for Computational Analysis of Social and Organizational System(CASOS), Carnegie Mellon University. It can track the relevant index of the group, identify the style of location and contrast the relation among networks, groups and individuals from the perspective of dynamic network. ORA also can recognize the key members, groups and vulnerabilities of the network between different time points, basing on which, carry on the further analysis. Compare with other social network analysis platform, ORA can support multiple data input form, and can instantly show the dynamic change of the network. This paper introduces the structure and functions of ORA, moreover, uses it to analyze the structure of a terrorist network, in order to find out the weakness of the organization.