A cable numerical model with fast solution speed is required in active truncated system. Because of intermediate equilibrium iterations, numerical model based on lumped-mass method’s solution speed is slow. To solve this problem, neural network was used to get equivalent model in time domain which reflects the motion relationship between upper point and truncated point of cable. This network model do not need iterative process so its solution speed can be more faster than lumped-mass method. A simulation platform was built by using Orcaflex and Matlab. In the process of simulation, lumped-mass method was replaced by neural network which is got off-line to do on-line computation. Comparison with results between full-depth system and truncated-depth system, it shows neural network is feasible in active truncated system.