High-altitude wind energy offers strong and stable wind resources but is limited by the lack of scalable manufacturing technologies for ultra-large airbag units with low gas leakage. This study proposes an innovative manufacturing approach, termed the Helix jointing method, which enables the continuous spiral fabrication of ultra-large airbag structures. The method addresses key challenges of conventional processes, including limited scalability, insufficient structural integrity, and poor sealing reliability. A dedicated manufacturing system was developed to ensure process stability and consistent joint quality. Experimental results demonstrate significantly lower gas leakage rates than those of commercial airbag materials. The proposed approach provides a scalable manufacturing framework for the practical deployment of airborne wind energy systems.