Shale wettability, as a critical parameter characterizing the multiphase coupling interactions among solid matrices, hydrocarbons, and non-hydrocarbon fluids within porous media, plays a pivotal role in elucidating hydrocarbon occurrence mechanisms and optimizing recovery efficiency. The wettability characteristics of globally representative shale formations were investigated, a four-aspects analysis encompassing organic geochemistry, mineral composition, microstructure, and experimental conditions was conducted to unravel the dominant factors governing heterogeneous wettability. The findings show that shales exhibit mixed oil-wet/water-wet behavior, with evaluation challenges stemming from spatial heterogeneity in organic-mineral assemblages and multi-scale pore structure heterogeneity. Current experimental methodologies, constrained by sample heterogeneity and inadequate replication of reservoir conditions, necessitate the development of multi-scale integrated evaluation techniques combining interfacial physicochemical analysis, microscopic imaging, and in-situ characterization. Wettability evolution is governed by organic matter thermal maturation pathways, diagenetic mineral alteration, and fluid-matrix interfacial interactions. However, systematic understanding of wettability superposition effects under multi-physical field conditions (temperature-pressure-fluid) remains deficient, warranting focused research on wettability reversal mechanisms and hydrocarbon enrichment effects during organic matter thermal evolution. Differentiated criteria and standardized evaluation protocols are imperative for assessing wettability in diverse shale hydrocarbon reservoirs and evolutionary stages. These insights advance the evaluation of heterogeneous wettability while providing theoretical references for deciphering hydrocarbon occurrence, enrichment, and extraction mechanisms in shale systems.