The invention discloses a small efficient polishing machine of a composite steel pipe. The small efficient polishing machine of the composite steel pipe comprises a rack, a base and the composite steel pipe. The base is fixedly arranged at the upper end of the rack, and the side wall of the front end of the rack is provided with a multifunctional controller. A clamping device is arranged at the center position of the upper end of a fixing plate. The composite steel pipe is arranged in an inner cavity of a clamping device. The upper end of a fastening device is provided with a hydraulic pump. The lower end of a hydraulic push rod is fixedly provided with an arc-shaped extruding block. The front end of the other side of the base is provided with a second servo motor. The two sides of a second lead screw are provided with second sliding blocks. One side of a vertical connection plate is provided with a motor. One side of a rotating shaft is provided with a pipe opening polishing device. Due to the fact that the small efficient polishing machine of the composite steel pipe is additionally provided with a first servo motor, a first lead screw and an arc-shaped clamping block, the composite steel pipe can be stably put into the inner cavity of the clamping device, and under the action of the arc-shaped extruding block, the stability of a pipe opening of the composite steel pipe during polishing can be guaranteed.