The powder coated composite steel pipe is coated with flame retardant and modified with epoxy resin powder. The coating has superior temperature resistance and does not burn or soften during long-term use. The coated composite steel pipe combines the high strength of ordinary steel pipes and the anti-corrosion performance of plastic grease products, with a compressive performance of 0 to 5.0 MPa. The usage temperature of coated composite steel pipes is 0-110 degrees Celsius, and the coating thickness is between 100 micrometers and 400 micrometers