In order to study the influence of laser process parameters on the cleaning quality of carbon steel surface contaminant layer, the Nd∶YAG quasi continuous laser was used to clean the surface rust contaminant of Q235 steel sample. The effect of laser cleaning on the sample surface was observed, and the working mechanism of laser cleaning contaminant ablation was analyzed. Then the cleaning effects and the cleaning quality with different process parameters such as laser energy density, cleaning rate, scanning width, defocusing amount, and repetition frequency were studied experimentally, and based on this, the orthogonal test was carried out to obtain the optimum laser process parameters to the Q235 steel; three-dimensional morphology, scanning electron microscopy, and energy spectrum were conducted to analyse the cleaning effect. And the optimal process parameters were obtained: Laser cleaning rate is 900mm/min, defocusing amount is 1mm, energy density is 7.6J/cm2, scanning width is 30mm respectively. Research shows that the surface roughness and three-dimensional morphology of the laser cleaning samples are improved, the roughness value of the laser cleaning samples is close to that of the rust-free samples, and the morphology of the laser cleaning samples is basically the same as that of the rust-free samples; after laser cleaning, the rust layer on the surface of the material is basically removed, and there are remelted microstructures on the surface. It can be concluded that laser cleaning can meet the cleaning quality requirements for carbon steel.