The invention discloses a spraying device for a steel pipe surface. The spraying device comprises a workbench, a support foot, a bracket, a spraying assembly, a feeding assembly, a support assembly, awaste box and an electric control cabinet. By setting the support assembly, one end of the steel pipe is sleeved on a second electric pushing rod, the other end of the steel pipe is sleeved on a third electric pushing rod, the second electric pushing rod and the third electric pushing rod are powered to run and extend to support the steel pipe, the support is carried out by an inner support method, and during the spraying process, the outer surface of the steel pipe can be sprayed without dead angles to improve the spraying quality of the steel pipe; by setting the spraying assembly, a mobilemotor is powered to run so that a nut seat is moved to one end of the steel pipe, the first electric pushing rod is powered to run so that a nozzle stretches above the steel pipe, a driving pulley drives a driven pulley to rotate, so that the movement speed of the nut seat is consistent with the rotational linear speed of a first rotary rod, the consistent spraying speed and the rotating speed ofthe steel pipe are ensured, and the consistency of the steel pipe spraying quality is improved.