The Portable Life Support System(PLSS),serving as a core component of the Extravehicular Activity spacesuit,must balance the requirements of life support protection and lightweight design.This study proposes a sandwich structure design based on Carbon Fiber Reinforced Polymer and validates the structural reliability of the composite backpack under launch/return segment overloads and space collision conditions through multi-scenario mechanical simulations.Simulation results demonstrate that the design achieves maximum deformations of 0.372 mm(mounting plate)under 6 g acceleration and 7.4 mm(skeleton)under 0.97 MPa impact loading,satisfying structural integrity requirements under extreme loads.The composite backpack manufactured by the autoclave molding process has passed the impact protection test under load conditions,verifying the manufacturing feasibility of the composite PLSS.This research provides a technically reliable pathway for lightweight design of EVA spacesuit structures by using composite materials,offering practical engineering value.