The invention discloses a method for preparing an ethylene polymer through microbubbles and belongs to the field of olefin polymerization. The method comprises the following steps: feeding a raw material gas into a polymerization reactor through a microbubble generator in a mode of microbubbles, and enabling the raw material gas to participate in a polymerization reaction under the action of a catalyst, wherein the microbubbles are gradually reduced or vanished in a slurry reaction system; and the raw material gas carried by the microbubbles is sufficiently dissolved into a solvent and uniformly mixed. The ethylene polymer prepared by using the method has the advantages of being narrow in molecular weight distribution range, high in tearing strength, high in impact strength, high in toughness, high in transparency, and the like.