There is the problem that the start and stop switch misoperation of NC device caused by the crosstalk between cables in the electric fast transient pulse group test. According to the actual test situation, CST cable studio software was used to make modeling analysis and simulation calculation. The simulation was mainly carried out from two aspects of cable spacing and cable type. The results show that the larger the cable spacing is, the smaller the interference intensity is. For single wire, when the spacing is 3 cm, the induced voltage peak-to-peak value is 5.42 V; when the wire spacing is 5 cm, the induced voltage peak-to-peak value is 3.08 V. At the 3 cm with higher interference intensity, twistedpair line and coaxial shielded line were used in the experiment. The results show that the coaxial shielded line has the best effect and the induced voltage peak-to-peak value is 0.68 V. Through the simulation, the crosstalk between the cables in NC device can be well simulated, so as to provide reference for the optimization of the NC device design, and then improve the reliability of the NC system.