Abstract: Avalanche transistor is a kind of ideal semiconductor device which can provide fast response and high pulse power at the same time, it can conveniently produce high power pulse with nano/subnanosecond rising edge. In this paper, three different types of circuits based on avalanche transistors are made. The performances of these circuits with different stages are compared. Besides, the effect of cable length on the pulse output is studied. The experiment results show that the pulse rising edge of circuit with cable as energy storage component can be divided into a fast rising stage (0.4 ns) followed by a much slower stage, while the output of circuit with capacitor as energy storage component only has the 0.4 ns fast rising stage, which indicate that the wave propagation in the cable affect the occurrence of an avalanche, therefore affecting the circuit output performance.