In order to meet the lightweight requirements of a fairing separation system, the work aims to design and develop a novel composite torsion spring with weight decreasing by 50% compared to traditional steel springs. In this design, the opposite-direction torsion of the inner and outer tubes was utilized to store elastic potential energy, and based on this, the theoretical relationship between elasticity and stroke, as well as other structural parameters, was analyzed. In practical applications for the specified model, with a support reaction force of 15 000 N and a stroke of 150 mm, the entire torsion spring structure was designed and its strength was validated through finite element simulation. The stress borne by the structure was within the material bearing range, and the design scheme met the use requirements. This design is suitable for directional separation of rocket and missile fairing, vibration protection of large equipment, and suspension stability of high-speed vehicles. It provides a new theoretical and practical foundation for the design and manufacture of high-performance springs.