Abstract: As the key component of the electromagnetic pulse simulator for steepening pulse output, the peaking capacitor is prone to surface discharge and breakdown in practical engineering applications. The photoelectric detection system can effectively analyze the surface discharge of insulation. Aiming at the technical problem of surface discharge monitoring of peaking capacitor, a set of photoelectric detection system for insulation surface discharge process is developed to detect the phenomenon of insulation surface discharge. Firstly, the design scheme of photoelectric detection system for dielectric surface discharge process is proposed. Secondly, the delay performance of the system is evaluated. Finally, the experiment of locating the surface discharge process of dielectric is completed, which verifies the feasibility of the photoelectric detection system. Experiments show that the system can effectively locate the discharge area.