Aiming at the problem of the effect of defocusing amount on the paint removal mechanism,a high-speed camera optical filter amplifier system was designed to photograph the dynamic process of paint removal at different defocusing amounts. The surface microtopography of paint removal at different defocusing amount was photographed via scanning electron microscopy,and the effect of defocusing amount on paint removal mechanism was analyzed by combining high-speed camera videos and scanning electron microscopy figures. The results show that at the defocusing amount of 0 mm,the paint is mainly removed by thermal stress,melting and gas impact. At the defocusing amount of +4 mm,the paint is mainly removed by thermal stress,melting and evaporation.