In the paper, the author expatiates on the design of the main body structures of immersed tunnels in respect of tube length determination, floating and freeboard, buoyancy resistance, structural strength and joint connection technology, presents the design concepts, influence factors and calculation methods of each part of immersed tunnels and summarizes the key technologies obtained in the design of the main body structures of immersed tunnels. The paper can provide reference for the design of the main body structures of immersed tunnels in the future.