Abstract: The beam transport system which is an important composition of laser facility target area provides guidance and collimation for laser beams. In this paper, the structural design of the beam transport system of SG-Ⅲ target area is introduced. The main performance of the beam transport system consists the stability, accuracy and cleanliness. In order to meet the stringent stability requirement, the dynamic stability of structure was improved and a new stability analytical method was proposed. The requirement of exact adjusting and fast online replacement was assured by the design of the Line Replaceable Units, the kinematic mounts structure, and the low-stress holding of the mirror mounts. Simultaneously, the clean conception was established in design, fabrication, and operation. The testing results of the installed part of the beam transport system indicate that the structural design satisfies the performance requirements of facility.