A novel ultrafast electronic pulse generator system consisting of a voltage charged transmission line(VCTL) and an intrinsic silicon optoelectronic switch has baon successfully developed. The switch in the circular circuit is illuminated by a laser pulse at 1.06 micrometers wavelength and 80 picoseconds width. A nanosecond square-wave electronic pulse with an ultrafast risetime and falltime(less than 200 ps) and a width determined by the length of the transmission line and switching efficiency limited by the load has been obtained.