The small number of pixels in APD array is the limitation of three dimension imaging resolution. A method based on optical phased array was proposed to improve 3D imaging resolution of APD array, the optical phased array was used to generate and scan the beam array, the number and position of the beam array were matched with the APD array. The divergence angle of the sub-beam in the beam array was smaller than the instantaneous FOV of a single pixel in the APD array, the APD array acquired multiple acquisitions of the target 3D information by scanning the sub-beam in a single pixel to improve the resolution of the APD array. The distribution of the beam array in the far field was simulated based on the two-dimensional scalar diffraction theory in Matlab, and the relationship between the divergence angle of the beam and the number of extended cycles was analyzed. Finally, the liquid crystal phase spatial light modulator was used as the optical phased array device, and the CCD was used to receive the echo signal, which further verified the feasibility of the proposed method.