Abstract: A high power short pulse can be generated by using pulse compression technology. The high impedance pulse forming line is initially charged, when its switch is closed, the energy flows to the lower impedance pulse forming line, as the voltage builds on the lower impedance pulse forming line, the output switch closes and the high power short pulse is generated and delivered to the output transmission line section. The principle analysis of pulse compression is presented. A GW level ns pulse driver is used as the high impedance pulse forming line with a characteristic impedance of 40 , an electrical length of 3.9 ns and an output pulse width of about 8 ns. The pulse compression device and impedance tapered line are developed, considering breakdown restrictions of lower impedance pulse forming line insulation and the output switch, the characteristic impedance and electrical length of pulse compression device are chosen as 6.5 and 0.5 ns respectively. By using the GW level nanosecond pulse driver, a pulse compression experiment is carried out. The experimental results show the pulse compression device output high power short pulse width is of 1.5 ns, and the power increase ratio is about 4, the experimental results are in good agreement with that from theoretical design.