Abstract: A landfill site was selected as research area to build a quantitative evaluation model for the pollution source intensity of the groundwater based on process simulation. This model was applied for landfill leachate to evaluate the pollution source intensity of cadmium in groundwater. Based on the study on the medium in unsaturated zone located in the research area and using the quantitative evaluation model of process simulation, several assumptions were proposed in relation to the reduction of cadmium in the unsaturated zone. The reduction function was then produced, based on which the quantitative evaluation method was developed for pollution source intensity in groundwater, and the reduction model correspondingly established. This model was applied to the research area, and the results showed that when the initial concentration of Cd in the leachate was 0.05 mg/L, the effective vadose zone was 13 m, the cadmium reduction was calculated at 0.013 and the entrance groundwater concentration was 5.13×10 ^-4 mg/L, after continuous penetration via 15.4 years. The simulated cadmium concentrations were consistent with the survey concentrations of this landfill groundwater. As the simulation result is comparatively fit with the monitoring result, the reliability of this evaluation model is verified.