Abstract: The micro-spallation behavior of materials under shock loading is a dynamic damage process resulting from the interaction between stress waves and the physical state of materials, which represents a critical focus in fields such as advanced national defense weaponry and inertial confinement fusion (ICF). This article provides an overview of the research progress on the formation and evolution of micro-spallation, covering three key physical processes: loading characteristics, micro-spallation formation mechanisms, and micro-spallation material distribution. Loading characteristics mainly involve the experimental acquisition of loading waveforms and pressure, the determination of whether the material enters an unloading melting or shock melting state based on the material phase diagram, and the re-confirmation of the phase state through surface temperature measurements. The micro-spallation formation mechanism mainly involves multi-phase equations of state, phase transition kinetics models, phase-dependent constitutive relations, empirical models such as spall damage models dependent on loading pressure, and refined numerical simulation methods capable of describing the heterogeneous distribution characteristics of materials. The micro-spallation material distribution mainly involves in-situ diagnostic techniques such as proton radiography and X-ray radiography, Asay-window-based diagnosis and inversion methods for local micro-spallation distribution, the micro-spallation spatial distribution obtained from recovery experiments, as well as theoretical predictions and numerical simulations. In addition, the study of micro-spallation behavior under complex loading histories or stress states is briefly introduced, which mainly involves the experimental design and diagnostic methods for planar recompression of micro-spallation, the construction of physical models and numerical simulations, and experimental research on spallation and recompression under complex stress loading conditions. Finally, based on the current research status, suggestions for future investigations are proposed.