Welding method for steel plate of ocean platform

The invention provides a technical scheme for a welding method for a steel plate of an ocean platform. The welding method comprises the following steps: 1) processing an edge; 2) assembling the edge into a K-shaped edge and fixing a water-cooling copper strip on the rear side of the edge, wherein the water-cooling copper strip is used for lifting a molten pool during a front backing weld process; 3) during the front backing weld process, preventing the water-cooling copper strip from upward arcing at a welding moment; 4) performing rear backing weld; 5) performing filling welding: alternately performing front and rear filling welding by using flux cored wire gas shielded welding or submerged-arc welding according to the condition of angular deformation of a welded steel plate; 6) performing cosmetic welding: using the flux cored wire gas shielded welding or the submerged-arc welding. The K-shaped edge in asymmetrical depths is adopted; the water-cooling copper strip is used for lifting the molten pool during the front backing weld process; a distance from a welding wire to a straight edge side of the edge is strictly controlled by the filling welding; the lower welding heat input is adopted for the cosmetic welding, and a welding joint with the welding joint forming meeting the CTOD (crack tip opening displacement) test demand on the welding joint of the steel plate of the ocean platform is lastly acquired.