The work proposes a three-laser-beam streak tube imaging lidar system. Besides the main measuring laser beam, the second beam is used to decrease the error of time synchronization. The third beam has n+0.5 pixels’ difference compared to the main measuring beam on a CCD, and it is used to correct the error caused by CCD discrete sampling. A three-dimensional (3D) imaging experiment using this scheme is carried out with time bin size of 0.066 ns (i.e., corresponding to a distance of 9.9 mm). An image of a 3D model is obtained with the depth resolution of <2 mm, which corresponds to ～0.2 pixel.