Abstract: Heterogeneity of subsurface aquifer causes organic-contaminated sites to commonly exhibit complex source zones, contaminant back diffusion, and concentration rebound. Traditional low-resolution site investigations relying on sparse borehole sampling are inadequate for accurately characterizing contaminant migration and distribution, which has become a key constraint on precise site remediation. High-resolution site characterization (HRSC) has gradually emerged as a core technology in the investigation and remediation of organic-contaminated sites. This paper systematically reviews the development history and research progress of HRSC. First, the fundamental principles of HRSC are defined from the perspectives of key heterogeneity scales and sampling volumes, with emphasis on its three core advantages: real-time monitoring technologies, dynamic sampling strategies, and data-driven decision-making. Accumulated evidence indicates that real-time direct-push sensing, in situ tools, and hydrogeophysical imaging can substantially improve the delineation of residual NAPL distribution, plume boundaries, and low-permeability mass-transfer behaviors, while iterative integration of multi-source data reduces key uncertainties in the conceptual site model (CSM) and improves decision relevance. HRSC is transitioning from “data acquisition” toward “data fusion and intelligent decision support” to enable risk-informed and efficient remediation decisions.