The invention discloses an electric height adjuster of an automobile seat and aims at providing an electric height adjuster with the advantage of enabling the fixing of a magnetic shoe to be firmer. The key point of the technical scheme is that a motor rear cover assembly comprises a motor shell, triangular magnetic shoes, a motor armature and a motor brush holder; four triangular magnetic shoes are arranged; the four triangular magnetic shoes are plastic-coated by using plastics to form a whole body; by using gluewater, the triangular magnetic shoes are fixed on the internal side of the motorshell; and the motor armature penetrates through the motor brush holder to be mounted into the motor shell on which the triangular magnetic shoes are fixed. As the four triangular magnetic shoes areplastic-coated together, the air gap consistency between the triangular magnetic shoes and the motor armature is preferably guaranteed, the vibration noise level of the electric height adjuster is increased, the novel triangular magnetic shoes are designed by sufficiently utilizing the structure of the motor shell, the overall dimension of the motor is effectively reduced, the weight of the wholeelectric height adjuster is reduced, the cost is reduced, the lightweight requirement of the automobile seat is preferably satisfied, the volume is small and the weight is light.