Abstract: 3D laser imaging includes intensity image and range image. The range image represents the depth of target, and can reflect the characteristics of the target much better, so the realization of high resolution range image is the central part of the 3D laser imaging technology. Because there are no domestic products of the APD array with the readout circuit (ROIC) currently, a high precision digital time conversion chip (TDC-GP21) was designed to measure the time of laser flying in the air, getting the distance information of the target to achieve high resolution range image. A scannerless 3D laser imaging precision timing circuit was designed, and the FPGA was taken to control time digital conversion chip. The simulation and experiment results show that the designed precise timing circuit can present a distance image of target.