In the process of production, transportation and assembly, cable assemblies can get a lot of electrostatic charge by friction, dragging, pulling and induction. These residual charges can be discharged when Electrostatic sensitive device connected with it and can cause the complete failure or potential failure of the electrostatic sensitive product. In this paper, the theoretical model of cable assemblies is established by analyzing the characteristics of cable assemblies, and the equivalent RF circuit is designed. The static discharge characteristics of the cable are analyzed and verified by simulation.