In order to deal with the problem of the laser gyro starting-up difficultly in cold condition, based on the principle of pre-ionization technique, the principle and specification of the LED exciting lamp is confirmed. The illuminance and energy distribution of cathode surface with different axial-installation position of exciting-lamp are calculated by the optical emulation software, and the layout of exciting light and axial-installation position is optimized. Theexperimentisdevelopedwhichvalidatedthatthenew-styleexcitinglampunits cansignificantlyimprovetheionization performance of laser gyro under cryogenic temperature, the ionization voltage is obviously decreased and the ionization time is obviously reduced. The one-time ignition success rate achievs 100% within -50～+75 ℃. The reliability of laser gyrowasfurtherenhanced