The invention discloses a microelectrolysis water purifier which comprises a main body, wherein the upper part of the main body is provided with a water inlet system and a water outlet weir; the upper part of the main body is also provided with an automatic water distributor communicated with the water inlet system; the lower part of the main body is provided with a gas-water separator and a microelectrolysis region; the automatic distributor is communicated with the gas-water separator through a water inlet down pipe; the gas-water separator is communicated with the microelectrolysis region; the gas-water separator is provided with an exhaust pipe; and the bottom of the microelectrolysis region is provided with a sludge discharge system. The microelectrolysis water purifier disclosed by the invention overcomes the defect of overhigh energy consumption in the existing sewage treatment, and has the advantages of simple structure, reasonable design, long service life, high treatment efficiency, low energy consumption for sewage treatment, zero energy consumption for backwash water cleaning, zero automation and the like.