Ultra-high altitude solar UAV has the characteristics of ultra-high aspect ratio and ultra-lightweight structure. Its aerodynamic layout parameters are not only closely related to the aerodynamic characteristics and static stability of the whole aircraft， but also indirectly determine the size of the structural deformation and structural weight of the aircraft. In addition， the existence of structural deformation will affect the aerodynamic characteristics and static stability of the aircraft in turn. Therefore， the comprehensive design of the ultra-high altitude solar UAV is a multidisciplinary comprehensive optimization problem which combines the aerodynamics， structure and stability. For this kind of design problem， sequential serial design method is less efficient， and it is difficult to get the overall optimal solution of the system. A comprehensive optimization design method for the aerodynamic/structural/stability of the ultra-high altitude solar UAV considering large structural deformation is established based on the idea of multidisciplinary parallel， which effectively improves the task load capability of the ultra-high altitude solar UAV under design constraints， and reveals the law of the influence of aerodynamic layout and structural design parameters on the task load capability of the ultra-high altitude solar UAV.