Abstract: Serious organic contamination was surveyed in the middle reaches of Hunhe River by assessing the alluvial fan for groundwater pollution. In order to investigate the migration regularity and impact factors of organic contaminants in the regional groundwater and to predict the degree of water pollution, the migration model of characteristic components of 1,2-dichloroethane (1,2-DCA) was established by numerical simulation method. We analyzed the migration regularity of 1,2-DCA in the groundwater of the middle reaches of Hunhe River and calculated the influence of water quality by 1,2-DCA. For the model, the initial recharge concentration of 1,2-DCA in Xihe River and Hunhe River were 4.50and 6.40μg/L, respectively, with a predicted period of 10years, considering the effect of diffusion, adsorption and degradation in numerical simulation. The results indicated that the maximum impacted area by 1,2-DCA in Xihe River was 1.80km², with maximum value of 3.50μg/L in the predicted period, while the impacted area in Hunhe River pollution zone was 3.78km², with maximum value of 5.00μg/L. The results showed a minor degree of damage to the regional groundwater quality. During the first 200days of the predicted period, the adsorption and biodegradation reduced the concentrations of 1,2-DCA in the contamination halo centers in Xihe and Hunhe rivers by 0.12and 0.10μg/L, respectively. Then, with the convection-dispersion as driving force for migration, the contamination of 1,2-DCA increased continuously. Due to the retardation of the cohesive soil to the migration of 1,2-DCA, the diffusion of the contaminants in Xihe River may be slower than that in Hunhe River.