The traditional plywood can't shape space concrete structure, and therefore, this article puts forward the concrete construction technology for 3D curved cantilever structure. This construction technology uses the supporting system of "steel plate" plus "steel keel" to prevent deformation during construction, uses steel plate cutting and assembly techniques to solve the problems of irregular changes in the surface normal direction, and uses computer 3D modeling to carry out detailed design and sample processing for the structural steel keel, which makes T-shaped steel keel structure accurately simulate the irregular changes in the longitudinal direction. Making full use of the drainage hole of the structure itself to enhance the whole modeling supporting system, this technology guarantees that the structural curve keeps smooth to meet the high standards of concrete appearances.