Abstract: A differential shaft for a strip-producing machine comprises a differential shaft mainly made up of a shaft core, a securing plug disposed at one end of the shaft core, a multiple of rolling tubes and partition rings each alternatively positioned with the other and sleeve joined in a sequence onto the shaft core thereof, and a fixing plug clamping tight of the partition rings and the rolling tubes thereof from the other end of the shaft core. The partition rings are stably located onto the shaft core via a pair of position pins engaged with a pair of stepwise retaining recesses of the shaft core with a ring gap A formed between the partition rings and the shaft core to reduce the friction thereof when the rolling tubes proceed with the strip production, effectively prolonging their lifespan in use.