The invention relates to the technical field of steel rolling, in particular to a machining method for steel for an SLED structure. The machining method includes the steps that in the process of flattening strip steel with a flattening machine, a first roller with a first roughness range is used for carrying out first-stage rolling on the strip steel, and the first roughness range is 0.55-0.65 micrometers; and after first-stage rolling, a second roller with a second roughness range is used for carrying out second-stage rolling on the strip steel, and the second roughness range is 0.15-0.19 micrometers. According to the machining method for the steel for the SLED structure, two stages of rolling are carried out on the strip steel in the flattening process, the first roller with the first roughness range is used for rolling in the first-stage rolling process, and the second roller with the second roughness range is used for rolling in the second-stage rolling process, so that the roughness of the strip steel is lowered, and the requirements of manufacturing the SLED structure are met.