Intense electromagnetic pulse will be generated during experiments at high power laser facility. The cable ports are the important routes of electromagnetic coupling. Highlighting the simulation on the electromagnetic pulse coupling of coaxial cables，which are widely used at high power laser facility, a simulation model on coaxial cable electromagnetic pulse coupling is established. The electromagnetic pulse coupling effect is studied with various cable lengths and two characteristic radiation directions. Simulation results show that the direction and length of coaxial cables will influence the electromagnetic pulse coupling. This study presents a good guide for electromagnetic simulation at high power laser facility and is helpful for cable selections，cable pavements and electromagnetic compatibility for precise diagnostics.