Laser cleaning is a green, safe, and efficient cleaning technology that has been widely applied in various fields, including electronic device cleaning, rust and paint removal, and cultural relics preservation. Although researchers worldwide have extensively explored enhancing laser cleaning efficiency and optimizing the cleaning process, there remains a lack of in-depth systematic studies on the underlying mechanisms of laser cleaning. Understanding these mechanisms is crucial for improving the optimization of laser cleaning process parameters, industrial applications, and the broader promotion of the technology. This paper reviews the interactions between laser and matter and systematically examines the laser cleaning mechanisms for micro-and nanoparticles, rust layers, paint layers, and other substances. These mechanisms include ablation, vibration, thermal stress, phase explosion, and stripping effects. Additionally, potential future research directions in laser cleaning mechanisms are discussed.