Aiming at the simulation problem of 3D flexible cable in equipment operation simulation training platform, the cable model is classified as two types which are named as constant length model and changeable length model. Then two different simulation methods are put forward according to their respective 3D shape characteristics. Firstly, the catenary method is adopted to describe the constant length model considering the gravity it deserved and the curve equation is deduced to be the final math model. Secondly, the changeable length model is equal to draw a 3D line according two given 3D coordinate points and cylinder with certain radius around the line can be drawn with calling OpenGL API. The rendering effect of each model is presented to prove the simulation feasibility. Finally, the realization mechanism called OpenGL call-back function combining with Vega is brought forward. It shows greatest traits on cable simulation in similar virtual reality system.