The nanosecond pulse laser is used to clean the corrosion layer and oil stain on the surface of 20 steel commonly used in petrochemical equipment.The optimized laser cleaning process parameters are obtained by orthogonal experiment.Under the cleaning process parameters of laser power 18 W,laser pulse repetition frequency 75 kHz, scanning speed 3 000 mm/s,the rust layer on the surface of 20 steel can be effectively removed. Under the cleaning process parameters of laser power 20 W,laser pulse repetition rate 75 kHz and scanning speed 2 250 mm/s, the oil stains attached to the surface of 20 steel can be effectively removed.The changes of material surface morphology before and after laser cleaning are analyzed,and the surface microhardness and corrosion resistance before and after laser cleaning are studied.The results show that laser cleaning can improve the microhardness of material surface without changing the corrosion resistance of material, so as to achieve the ideal laser cleaning effect.