The invention relates to a motor assembly, in particular to a motor shaft used for outputting power generated by a motor, and a manufacturing method of the motor shaft. The motor shaft comprises a shaft body, and a shaft sleeve is arranged on the shaft body. The motor shaft is characterized in that the shaft sleeve and the shaft body are of a split type structure and are in interference fit. The manufacturing method of the motor shaft sequentially comprises the steps of material selection, heating, press fitting and finish machining. The procedure for machining the motor shaft is simple, time consumption is low, the production efficiency is high, the production cost is low, and the workblank allowance is small.