Earthquakes occur mainly on active faults. Fault slip is closely related to seismicity and is thus widely discussed in Geosciences, Seismology, and Engineering. Slip experiment is a necessary and powerful tool to explore the physical processes and mechanisms of pre-earthquake, earthquake, and aftershock. This work reviews the experiment study of fault slip from field experiments, laboratory experiments, and numerical experiments, which helps to provide a clear understanding of earthquake mechanics. We show that there are five main influencing factors in the study of fault and earthquake: stress, velocity, material, fluid, and temperature. Around these factors, the process of shear failure and rupture nucleation, the weakening and strengthening of fault, the characteristics of slip behavior, and the signal characteristics of slip are discussed. These works do not only have the potential to advance the understanding of the earthquake mechanism, but also to guide the prediction and control of earthquakes disasters. Furthermore, there are still several issues that need to be better discussed, such as the influence of stress disturbance on fault stability, the scale effect between natural faults and laboratory faults, and the role of roughness in the friction and slip characteristics of faults. Moreover, it is also necessary to consider the earthquake precursors of multiple signals such as seismic velocity, electrical signal, and magnetic signal, as well as effectively capture them in combination with artificial intelligence technology. It will be new breakthroughs in the prediction of earthquakes.