The chemical elements on the surface of tailing sand were analyzed and calcium was found to be the main element causing the chemical clogging in Shibangou Tailing Reservoir. Calcium chloride solution was added to the samples to change the calcium content. The seepage test equipment and the nuclear magnetic resonance (NMR) system were used to observe the time series changing pattern of the porosity, pore distribution and permeability coefficient of the tailing sand under the action of different solution concentrations and hydraulic gradients, and then the influencing factors were analyzed. The results show that the NMR system can accurately obtain the porosity and pore distribution of the tailing sand under different conditions. The larger the solution concentration and the longer the action time, the more obvious the clogging effect gets, the smaller the porosity, pore size and permeability coefficient become. The permeability damage caused by high hydraulic gradient will slow down the clogging process. There is an obvious negative exponential relationship between the permeability coefficient and the action time under different concentrations. The established empirical model for the prediction of the permeability coefficient can provide some reference for the seepage control analysis and safe operation of tailing reservoirs.