Abstract: Multi-beam combining is an effective method for improving the power and far-field beam uniformity of pulsed laser diode. It can also increase the imaging range, and the laser active imaging system can be miniaturized. First, the combining beams distribution was derivated using Exponent-Gaussian model. Then the influence of some parameters such as the angle of the laser diodes away from horizontal line, the spacing between laser diodes and the lasing delay times were simulated with Matlab. Finally, the range-gated imaging beyond 1.5 km was obtained. It can be concluded that multi-beam combining can improve the performance of the range-gated imaging by comparing the imaging of different numbers of the laser diode.