Laser cleaning of rust layer on the surface of carbon steel was studied by fiber laser, the effect of laser scanning speed on the removal quality of rust layer was studied by white light interferometer, optical microscope and Raman spectrometer. The results show that, when the laser scanning speed is less than 2 000 mm/s, the high spot overlap rate and strong heat accumulation effect, lead to the melting and recondensation of the substrate surface, and a secondary oxidation occurs on the sample surface, which result the formation of a complex iron oxide film, at the same time, the surface roughness of the sample is the smallest. When the laser scanning speed is increased to 3000 mm/s, the rust layer on the surface of the sample is completely removed, the color of the metal substrate is exposed, and the secondary oxidation on the surface of the substrate is weakened. When the scanning speed continues to increase, due to the low spot overlap rate, the laser energy absorbed by the rust layer is less, only part of the rust layer is removed, the residual rust layer begins to appear on the surface of the sample, and with the increase of scanning speed, the residual rust layer and surface roughness increase. Better rust removal effect can be obtained by adjusting the scanning speed, after optimization the process, when the laser power is 120 W, the rust removal efficiency reaches 1.5 m²/h.