The utility model discloses a membrane distillation device for salt-containing wastewater treatment. The membrane distillation device comprises a pretreatment device, a raw material liquid pump, a heat exchanger, a liquid storage tank, a circulating pump, a heating device, a membrane distillation system, a heat exchange system, a distilled water collecting tank and a vacuum pump, wherein the pretreatment device, the raw material liquid pump, the heat exchanger, the liquid storage tank, the circulating pump, the heating device, the membrane distillation system, the heat exchange system, the distilled water collecting tank and the vacuum pump are connected in sequence. After pretreatment is carried out on salt-containing wastewater by the pretreatment device, the salt-containing wastewater is fed into the heat exchanger to be preheated through the raw material liquid pump, and is mixed with circulating liquid in the liquid storage tank to obtain mixed liquid, the mixed liquid is pressurized by the circulating pump and fed in the heating device to be heated, then membrane distillation is carried out through the membrane distillation system, generated vapor enters the heat exchange system for condensation heat exchange, the vapor is condensed and enters the heat exchanger to heat the salt-containing wastewater, then the vapor enters the distilled water collecting tank, and generated low-temperature material liquid returns into the liquid storage tank to be mixed again for membrane distillation. Through the membrane distillation device, after the salt-containing wastewater is treated, the salt removing rate of generated distilled water is 98 percent, and crystals generated by concentrated liquid can be recycled.