The authers have developed avalanche transisitors based pulser for use as a electro-optical switch driver. These transistors are mounted on microwave structure board. The circuit can generate a electrical pulse with peak voltage of 6.4 kV,peak current of 128A,voltage amplitude of 5 kV,fall time of 990 ps,in 50Ω load. The trig jitter is less than ±15 ps;trig delay is about 30 ns.