The invention relates to an inner ring fixing device for a robot automatic assembly bearing production line and a using method thereof. The inner ring fixing device comprises a front bracket, a rear bracket and an outer tube with the two ends connected with the front bracket and the rear bracket correspondingly, and an inner ring baffle is fixed to the front bracket, is provided with a ball fixingball stopping block and a stopping rod and is provided with an inner ring stopping block in a horizontal sliding manner; and the outer tube is provided with a support shaft connected to the inner ring stopping block, and the support shaft is sleeved with a spring located on an own limit shoulder and the inner wall of the outer tube. The inner ring fixing device achieves integrated application ofa robot in the bearing assembly process, realizes precise positioning of inner ring placement, achieves the function of guiding ball filling during inner ring assembly, better promotes the automationoperation, and has the advantages of simple operation and convenient use.