Aimed at the complex cave and reservoir group project construction tunnels, ventilation shafts, working surfaces, intersections and other difficult problems, based on the “818 Project”, the rapid construction methods and support technologies for complex cave groups have been studied. A construction method for five parallel tunnels with small spacing and shallow burial of super-large cross-section was proposed, optimizing the four-step construction method for single tunnels. Numerical analysis and field monitoring data show that synchronous construction of five parallel super-large cross-section tunnels increases the vertical stress of surrounding rock while reducing the vault stress. Surface settlement and surrounding rock deformation are within the control range, with the surrounding rock stability coefficient being 0.882, requiring timely and strengthened initial support. The parameters of steel arch removal and advanced small pipe were optimized at tunnel intersection portals to ensure construction safety at intersections between lateral connection tunnels and super-large cross-section tunnels. By considering tunnel cross-section size, surrounding rock pressure, lithology, and mechanical properties of surrounding rock, initial support parameters were optimized, resulting in good support effects. The research findings further enrich construction methods and support technologies for complex tunnel groups.