A manufacturing method for a motor core includes a preparing step, a coating step, a stacking step, and a forming step. In the preparing step, the silicon steel sheets are cleaned and dried. In the coating step, an electrically insulating colloid is coated between each pair of adjacent silicon steel sheets. In the stacking step, the silicon steel sheets on which the electrically insulating colloid is applied are stacked on each other to form a layered structure. In the forming step, the stacked silicon steel sheets are subjected to a colloid curing process so that the electrically insulating colloid forms a thermosetting plastic. This reduces the chance of forming eddy currents, reducing the eddy current loss of the motor core during operation.