Laser radar technology, widely used in topographic reconnaissance, land survey, as well as construction survey, is considered as one of the most useful technologies in accurate measurement nowadays. Through long-term research, we have developed three-dimensional laser scanning system with measurable distance as far as 100 meters, 300 meters and 1000 meters. Hence we have accumulated rich experiences in extending the measurable distance, which, as we known, is the one of the core indicators of the three-dimensional laser scanning system. Measurable distance not only reflects the performance of the system, but also decides its usage and application field. It is related to the laser power, receiver’s perception ability, atmospheric transmittance, reflectivity of target and etc. In this paper, we mainly analyze the relation of measurable distance with each of the four parameters. Then we propose our design to extend measurable distance, and finally we verify our method through simulations and experiments.