The invention discloses a 3D printing system and technology of a coaxial sprayer and an enhanced type hollow gel pipe of the coaxial sprayer. The 3D printing system comprises a 3D printing platform, two sets of feed devices, the coaxial sprayer, spraying devices and a control system. Furthermore, the coaxial sprayer is composed of an inner pipe, an outer pipe, two feed ports, a sealing gasket and a welding piece. By means of the coaxial sprayer, the coaxiality between the inner pipe and the outer pipe at the front end of the sprayer is better guaranteed through the welding piece, and closing between the inner pipe and the outer pipe is guaranteed through the sealing gasket. According to the printing technology of the enhanced type hollow gel pipe, ferric chloride spraying further reacts with the hollow gel pipe, and the mechanical strength of the hollow gel pipe is improved. The coaxial sprayer and the spraying devices are arranged on the XY printing platform, the control system controls running of the printing platform, the feeding device and the spraying devices, and in combination with the printing technology of the enhanced type hollow gel pipe, printing of the enhanced type hollow gel pipe is jointly combined.