Abstract: It was necessary to use the Pulsed Laser Radar to measure the distance with the deep space target or space small target. When the distance varied from tens of kilometers to tens meters, the energy range that photoelectric detector received reaches above 60 dB. To assure the detector not saturated, the multiplex AGC(Automatic Gain Control) technology was required. Except for the electronics method, a method of adjusting aperture of receive optical automatically was put forward, which made the luminous flux of detector changes 2 times by adjustment of Motorized lens' aperture regulation ring step by step, which was driven by direct current motor. The driven and control circuits of motorized lens were designed and realized to adjust aperture, zoom and focusing through FPGA software. Optical path was established to calibrate the aperture. The result showed that aperture can be divided into 8 levels, which have good repetition characteristic. This make it is impossible to realize laser ranging with centimeter grade precision in the whole detecting field.