The invention discloses a method and a device for promoting free radical conditioning and pressure-vertical electric field dewatering of sludge through microelectrolysis. The method comprises main steps as follows: sludge is stirred, a direct-current electric field is applied, and iron powder and a conditioning agent are added for conditioning; the sludge enters a pressure-vertical electric fielddewatering device for dewatering. According to the method, the microelectrolysis process of an iron powder induction electrode is enhanced through the electric field, generation of Fe<2+> is promoted,activation of sulfate is realized, sulfate free radicals and high-valence iron ions are produced, electrolysis-oxidation-flocculation coordinated conditioning is performed on the sludge, the functions of cracking of the sludge structure, bound water release and floc reconstitution are played, and the dewatering effect of the conditioned sludge in the pressure-vertical electric field is enhanced.The dewatering efficiency is high, the water content of the sludge can be reduced to 50% or below, and the water content of the sludge is effectively reduced. Besides, the method and the device also have the advantages that the reaction time is short, operation is simple, the application range is wide and the like.