By controlling the light wave-form of Xe lamp with insulated gate bipolar transistor(IGBT) and using the periodic long-pulse chopper technology,a long pulsed medical Nd:YAG laser was designed.it can enlarge the safe operating area(SOA) of the IGBT module,which can make the IGBT work more stably;it has higher electronic-optic efficiency because of its higher pumping power;it can reduce the skin thermal effect and prevent the skin from heat injury during the hair removel treatment.So a long phase laser with wavelength of 1 064 nm,energe of 50 J,pulse duration from 9 ms to 99 ms,was obtained.