The invention discloses a landfill leachate membrane concentrated solution reduction and resourceful treatment system and method. The treatment system comprises an immersion combustion evaporation device, an industrial salt preparation device, a miscellaneous salt resourceful treatment device and a waste residue treatment device. The industrial salt preparation device comprises a forced circulation evaporation crystallizer for preparing industrial salt KCl and NaCl by using a saturated membrane concentrated solution, a flash evaporation cooling crystallizer for preparing industrial salt NaNO3and Na2SO4 by using mother liquor discharged from the forced circulation evaporation crystallizer, and a sodium sulfate evaporator; the miscellaneous salt resourceful treatment device comprises a reaction kettle, concentrated sulfuric acid is added into the reaction kettle, miscellaneous salts generated after the industrial salts are prepared enter the reaction kettle to react to prepare NaHSO4 and HCl, and reacted waste salt enters the waste residue treatment device to be formed so as to be solidified and buried. According to the treatment system, separation of the industrial salts is achieved while the membrane concentrated solution is subjected to submerged combustion evaporation reduction treatment, circulation of the salt in the environment is reduced, the salt is recycled, and the economical efficiency and environmental friendliness of landfill leachate membrane concentrated solution treatment are further improved.