Profile extrusion process mainly includes billet size selection, extrusion temperature determination, metal flow velocity determination, process formulation, lubricant and application mode selection. Solid round section ingots are mostly used when extruding profiles. Hollow round section ingots are only used when extruding hollow profiles with simple inner hole shape and large size. The size of ingot determines the quality of profile and the technical and economic indexes of extrusion process. When selecting ingot, its volume should reach the maximum value to improve the yield. When several extrusion cylinders of different sizes can be used, the ingot with the smallest diameter should be used. The temperature range, metal flow velocity, lubricant type and lubrication mode of profile extrusion are the same as those of steel pipe extrusion.Classification of section steel: according to different smelting quality of steel, section steel is divided into ordinary section steel and high-quality section steel. According to the current metal product catalogue, ordinary section steel is divided into large section steel, medium section steel and small section steel. According to its section shape, ordinary section steel can be divided into I-beam, channel steel, angle steel, H-section steel, round steel, etc.