The invention belongs to the field of the power electronics, and specifically a pulse forming network based on a cathode short-circuit grid-controlled thyristor (CS-MCT). The pulse forming network mainly comprises a charging loop composed of a DC power supply and a charging resistor, N-step pulse forming network part, a discharging loop composed of a one-way conducting diode, a CS-MCT, a freewheeldiode, a two-way clamping diode and a load, and a device grid control part, wherein the CS-MCT adopts the four-end connection, and a grid cathode (kevin cathode) is added in comparison with the normal three-end device. The pulse forming network disclosed by the invention has the advantages that the influence on the grid cathode loop by instantaneous high voltage induced by a cathode inductor canbe effectively inhibited, and the breakdown invalid of the grid caused by the overvoltage is avoided; the grid only has the effect of triggering the conduction, when a device enters a thyristor work mode after the latch is conducted, the electric-conducting modulation effect is further reinforced, the conductivity is free from the control of the grid and the limitation of the saturation current, and the greater pulse current can be realized under small area.