Time-slicing images captured by laser-based active range-gated imaging technique are easily affected by the energy of the laser pulse and gate time. Consequently, the contrasts of time-slicing images are poor. Furthermore, the edge information and structural information are seriously lacked in the reconstruction of three-dimensional imaging. Therefore, an image preprocessing method for time-slicing images based on guided filtering combined with bilateral filtering is proposed to overcome this limitation. The proposed method changes the distribution of pixel information of time-slicing images within the error range to obtain high-quality three-dimensional reconstruction results. First, the guided filtering is employed to enhance edge information and recover structural information within the image. Then, the bilateral filtering is employed to compensate for defects introduced in the previous step (i.e., increasing invalid points). As a result, the uniformity of the image is stabilized. Experimental results demonstrate that three-dimensional reconstruction after applying the proposed preprocessing method achieves better performance in enhancing edge information, structural information, and image uniformity without sacrificing distance accuracy.