A self-reinforced irregularly-shaped section, comprising a section and a reinforcing lining provided in a cavity of the section. The section is 100 parts of ASA, SAS, ABS, AS and/or AES sections. The reinforced lining is 5-120 parts of a reinforced styrene-based copolymer composite material. The reinforced styrene-based copolymer composite material comprises the components of: a styrene-based copolymer 20-55 parts; PBT or PMMA 5-30 parts; and a reinforcing agent 30-65 parts. A manufacturing method for the self-reinforced irregularly-shaped section is such that the reinforced styrene-based copolymer composite material is manufactured first, then a main machine and an auxiliary machine designed perpendicular to the main machine are employed for joint extrusion, the main machine is used for extruding the section, the auxiliary machine is used for extruding the reinforced styrene-based copolymer composite material, the main machine and the auxiliary machine extrude concurrently, and the self-reinforced irregularly-shaped section is produced when molded and cooled into form. The self-reinforced irregularly-shaped section prevents the problem of the reinforced lining peeling from the section during transport, mounting, and use, allows low-temperature molding, and has great production stability and molding stability.