Abstract: The welding deformation of a type of flying sheave for tethered balloons is difficult to control. It is inconvenient to disassemble and maintain the flying sheave. And the monitoring function of products is inadequate. To solve these problems, a general design requirement is put forward in this paper based on the function and safety requirements of the flying sheave and optimization design is carried out from manufacturing process, maintenance and on-line measurement. As a result, welding deformation is reduced, measurement function for tensility and drift angle of the tether is added, and the on-line separation of flying sheave and tether is realized conveniently, which is useful for maintenance and replacement of the flying sheave and tether.