In order to improve the membrane distillation and its mass transfer efficiency, this article bases on the new thermoelectric refrigeration of flat plate type membrane distillation and analyzes the performance of the new cold chamber semiconductor. It mainly carries out a numerical simulation analysis for the difference among many handed structure parameters of heat fault cavity, obtains 2mm membrane heat fault cavity flow field and temperature field. A comparative analysis with different value of boundary layer vortices and temperature gradient. The simulated results show that: groove width is 3mm, vortices value of 60°angle diversion of water disk is 0.088(1/S), temperature gradient is 0.02(℃/mm),it weakens the temperature polarization and concentration polarization of outside the boundary layer at the membrane surface , it lays the foundation for improving the membrane distillation and its mass transfer fluxes methods physical mechanism.