Timing system was used to measure the timeofflight(TOF) of laser pulse in light detection and ranging(LIDAR). Performance of a LIDAR system is directly influenced by the properties of the timing system. A timetodigital converter(TDC) based on FPGA was designed for photoncounting LIDAR. By integrating the delay line interpolation into FPGA, the designed TDC could measure the TOF with fine accuracy and resolution. The performance of the TDC and its application in photoncounting LIDAR were analyzed and studied experimentally. Eventtiming of 9 channels was implemented with this TDC, with a resolution of 29 ps and a timingaccuracy of 37 ps. Using a LIDAR system equipped with the TDC, threedimensional imaging can be realized with time accuracy of 421 ps and 6.3 cm resolution in space.