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Brackish water poses a health hazard worldwide, but especially to rural residents in China. In this study, a direct contact hollow fiber membrane distillation system was established based on a filter-pretreated hot spring resource in the Jiaodong area of China. The effects of the operating temperature, flow rate, and composition of brackish water on the properties of membrane distillation were investigated. A multistage system model was established using the Aspen plus platform and the economic cost of the system was analyzed. The results showed that the permeate flux could reach 12.599 kg/m2·h. The effect of the MgSO 4 content of the brackish water on the flux decreased above 20 g/L. Electron microscopy and elemental analysis showed that carbonate crystallization occurred mainly in the scaling part. The simulation results showed that the inlet temperature of the feed side had major effects on the increase in the flux and gain output ratio. A parallel layout was more effective and the regenerator improved the gain output ratio (GOR), with a 30% maximum increase for the system. The unit water production cost decreased to $18.2/m3 as the subsystem number increased to 10. These findings may help to improve the performance and economic benefits of this special type of distillation system. • Geothermal direct contact membrane distillation system for purifying brackish water • Scale removal method proposed for the membrane distillation system • Heat and mass transfer models established for the system • Methods for improving the flux, gain output ratio, and economic benefits [ABSTRACT FROM AUTHOR]