The invention relates to the technical field of electric motors, and discloses an electric motor for driving oil field mechanical equipment. The electric motor comprises a machine base, wherein a front end cover is fixedly arranged at the left end of the machine base through a bolt, and a rear end cover is fixedly arranged at the right end of the machine base through a bolt; the two side faces, far away from the machine base, of the front end cover and the rear end cover are provided with bearing bases respectively; an outer ring is fixedly arranged in each bearing base; and an outer rail is arranged in the inner surface of the outer ring. The base oil in an oil storage cavity is supplied upwards through fine gaps inside cotton threads, so that the base oil in the oil storage cavity can beimmersed into the braided fabrics through the cotton threads, and the base oil is coated outside a steel ball through the braided fabrics, wherein the lithium-based grease is repeatedly rolled in therolling process of the steel ball, and the base oil is uniformly mixed with the lithium-based grease, so that the purpose of supplementing the base oil to the lithium-based grease is achieved; a worker does not need to replace the lithium-based grease in the bearing periodically, so that the labor amount of workers is reduced.