【Objective】There are many factors governing the migration of non-aqueous phase liquids (NAPLs) in the subsurface because of the simultaneous flow of immiscible phases in a multiphase system including NAPLs, water and air after the leakage of NAPLs. The driving mechanism of NAPLs in the site soil-water system is complex, and predicting and visualizing the spatial-temporal distribution and changes of pollutants are prerequisites for scientific and standardized green and low-carbon remediation and control of soil and groundwater pollution. 【Method】This article is based on the WebGIS geographic information system platform and incorporates self-developed organic contamination multiphase flow-temperature-chemical multi-field coupled simulation and Cesium visualization technology. It integrates a Browser/Server (B/S) architecture-based spatial distribution simulation and visualization system for organic pollutants in the soil-water system of contaminated sites.【Result】The visualization system can be applied to the integrated management of organic pollution site investigation and monitoring data, graphical modeling of organic pollution spatiotemporal distribution, and visual expression of the entire multi-field coupling pollution process. The system is applied to characterize the spatiotemporal distribution and variation of the di-(2-Ethylhexyl) Phthalate (DEHP) contaminant in the soil and groundwater of a certain organic pollution site in the South. The overall fit of the system reaches an R-value of 0.91, with simulation errors less than 30%. Based on the coupling model, the system further predicts the attenuation process of DEHP. It calculates the proportions of NAPL that remain adsorbed as a residual phase (50.3%) and those that undergo degradation due to volatilization (11.3%) and dissolution (7.4%) within the simulation period. 【Conclusion】Due to difficulties in acquiring on-site parameters, the model used physical and chemical properties of soil, water, gas, and NAPLs referenced from relevant literature, resulting in some uncertainty in the simulation results at the site scale. Nevertheless, the overall trend of predicting the spatiotemporal distribution of DEHP is reasonable and aligns with the coupled mechanisms of multi-phase flow, temperature field, and chemical field in organic pollution sites. Through visualizing different scenarios of organic pollutant spatiotemporal distribution and prediction, the visualization system can provide an information platform for organic pollution risk assessment, precise prevention and control, and comprehensive management of contaminated sites.