A high power pulse generator is described，which has been used in a bounded-wave Electro Magnetic Pulse(EMP) simulator. The peak value of the generator output voltage is above 100 kV，the rise time of output waveform 1.8 ns，and its pulse-width 40 ns. The diameter of the generator is 18 cm，and its length 97 cm. The generator, with compact configuration，also can work in a repetitive mode. This system can be adopted to evaluate and improve the viability against Nuclear Electro Magnetic Pulse(NEMP) of weapons.