Aiming at the actual demand for long pulse width of 308 nm excimer laser for medical use, a Simulink simulation model was proposed to guide the scheme of extending the laser pulse width, and experimental research was carried out. First, the effectiveness of the simulation model of the excitation circuit of a typical excimer laser discharge was established and verified. Second, the discharge excitation model of a 4-level LC peaking circuit was established based on the principle of pulse forming network, and the design and parameter selection of specific laser structure were carried out. Experiment with a 308 nm excimer laser, an energy storage capacitor of 60 nF and a voltage range of 20-29 kV was completed. By changing the structure and parameters of excitation circuit, the laser pulse width was extended from 30 ns to 60 ns, and when the voltage value of energy storage capacitor was 28 kV, the output energy was up to 407 mJ, the transfer efficiency of laser pulse energy was increased from 1.531% of the typical structure to 1.73%, and the high energy transfer rate under the condition of the long pulse output of discharge excitation 308 nm excimer laser was realized. It verifies the validity and effectiveness of the Simulink simulation model. The guiding significance is to provide the basis for the design and application of the practical long pulse width excimer laser.