Abstract: Joint clearance，unsealing and poor stress state often appear in the assembly process of the rigid coaxial line．These problems affect the performance of the rigid coaxial line system greatly．Therefore，the solution to the problems in assembly process is urgent in engineering applications．In this paper，a method of optimizing the function of the rigid coaxial line system is introduced by controlling and monitoring coaxial line clearance，dividing the installation sections，setting test points，inspecting incident and reflected power and adjusting the system requirements before its installation．The practice shows that these methods are maneuverable and practical．Meanwhile，these methods can optimize the assembly process and improve the reliability of the rigid coaxial line system．