Abstract: The objective of this work is to develop a numerical model to stimulate organic variation accurately in the leachate,to provide support for landfill management,and to minimize the risks of environmental pollution.A mathematical model simulating organic variation in the leachate of bioreactor landfill was presented and demonstrated based on mass balance of contaminants and degradation kinetics.The model was solved numerically using a fourth-order Range-Kutta algorithm and the model parameters were validated by monitoring data.Efficiency assessment and T test were performed for simulating results,and the efficiency coefficients were respectively 0.776 6 and 0.919 3 for column 1 and column 2.T test result showed that the simulating results and monitoring data have no marked difference.Given the limitations in data capture,a sensitivity analysis was performed,highlighting the model's response to changes in input variables.The ^ensitivity index of k₁ was more than that of k_ls,and it was the least for k_sg Moreover,illustrative examples of the model's output are presented to demonstrate effects of data uncertainty on organic concentration by Monte Carlo method.Thus,the numerical model presented in paper can stimulate the organic variation accurately and comprehensively in the complexly changeful landfill.