Laser effective utilization rate is low because the gap between adjacent pixels in APD detectors used in laser 3D imaging is too large. Aiming to the question, the array beam laser 3D imaging technology was proposed. A laser beam of the laser radiation source was diffracted into sub-beams in array with a liquid crystal spatial light modulator, so that the laser beam can be divided into sub-beams corresponding to the array APD detector. The positions of the laser beam and array APD detectors were adjusted, so that the laser beam can irradiate on an object and focus on the effective array pixel of APD detector, the utilization efficiency of laser beam was improved. The composition and working principle of array beam laser 3D imaging system were introduced. The scheme to realize the array beam by using liquid crystal spatial light modulator was proposed The prototype of the array beam laser 3D imaging system was studied, and the result of laser array beam using the prototype was verified. The experimental result shows that 3D imaging range reaches 510 meters with peak power 10 kW, pulse width 8 ns, and 8×8 APD detector fill factor 2/3, the effect distance increases by 39.1%, compared with the laser 3D imaging system without array beam.