In order to improve the ranging accuracy, the internal timing module of the laser rangefinder is studied. The factors affecting the ranging accuracy of the laser rangefinder are analyzed. An external delay chain chip is used as the delay line to design and make a timing generator based on the field programmable gate array (FPGA) development board. The test results show that the designed timing generator can achieve 11 ps timing resolution and a maximum data rate of 600 Mbit/s, which has achieved the expected target.