A motor structure, comprising: a housing, which is formed of a first casing member and a second casing member that are fastened to and connected with each other, a support and separation board being arranged and clamped between the first and second casing members (11, 12); and a drive unit, which is arranged between the first and second casing members (11, 12) of the housing and is supported by the support and separation board, the drive unit comprising an electromagnetic device mounted to one side surface of the support and separation board, the electromagnetic device comprising an output axle penetrating through the support and separation board, a transmission axle being arranged between the first and second casing members (11, 12) of the housing for transmitting power to outside of the housing, the transmission axle penetrating through the support and separation board, a reduction and transmission mechanism being arranged in a loading path between the output axle of the electromagnetic device and the transmission axle, wherein the reduction and transmission mechanism comprises a reduction gear arranged on one side surface of the support and separation board that is opposite to the electromagnetic device to be in mating engagement with and driven by the output axle; and the reduction gear comprises a first drive wheel coaxially rotatable therewith, and the transmission axle is provided with a second drive wheel corresponding to the first drive wheel, and a drive member is arranged between the first and second drive wheels (24, 26) to establish a transmission arrangement, wherein a rotational speed ratio between the output axle and the transmission axle is variable by means of a change of a diameter ratio between the reduction gear and the first drive wheel and between the first drive wheel and the second drive wheel, characterized in that the support and separation board comprises a protection frame mounted thereto at a location corresponding to where the output axle and the reduction gear are set in mating engagement with each other. a housing, which is formed of a first casing member and a second casing member that are fastened to and connected with each other, a support and separation board being arranged and clamped between the first and second casing members (11, 12); and a drive unit, which is arranged between the first and second casing members (11, 12) of the housing and is supported by the support and separation board, the drive unit comprising an electromagnetic device mounted to one side surface of the support and separation board, the electromagnetic device comprising an output axle penetrating through the support and separation board, a transmission axle being arranged between the first and second casing members (11, 12) of the housing for transmitting power to outside of the housing, the transmission axle penetrating through the support and separation board, a reduction and transmission mechanism being arranged in a loading path between the output axle of the electromagnetic device and the transmission axle, wherein the reduction and transmission mechanism comprises a reduction gear arranged on one side surface of the support and separation board that is opposite to the electromagnetic device to be in mating engagement with and driven by the output axle; and the reduction gear comprises a first drive wheel coaxially rotatable therewith, and the transmission axle is provided with a second drive wheel corresponding to the first drive wheel, and a drive member is arranged between the first and second drive wheels (24, 26) to establish a transmission arrangement, wherein a rotational speed ratio between the output axle and the transmission axle is variable by means of a change of a diameter ratio between the reduction gear and the first drive wheel and between the first drive wheel and the second drive wheel, characterized in that the support and separation board comprises a protection frame mounted thereto at a location corresponding to where the output axle and the reduction gear are set in mating engagement with each other.