The invention discloses a servo adjustable tool for brake disc machining. The servo adjustable tool comprises a tool apron body, an upper end face tool apron, a lower end face tool apron, a movable driving mechanism and a pressing limiting mechanism, and the upper end face tool apron is mounted at the bottom of the tool apron body; the tool apron body is internally provided with a mounting groove,the upper portion of the lower end face tool apron is arranged in the mounting groove, the lower portion of the lower end face tool apron is located outside the mounting groove, an upper turning toolis mounted on the upper end face tool apron, and a lower turning tool is mounted on the lower portion of the lower end face tool apron; the movable driving mechanism comprises a servo motor, a motorseat, a screw rod, a lead screw nut and a bearing seat, the motor seat is mounted on the top of the bearing seat, and an output shaft of the servo motor is connected with the upper end of the screw rod; and the lower end of the screw rod penetrates through the bearing seat and then stretches into a vertical groove formed in the lower end face tool apron, the lead screw nut is in threaded fit withthe screw rod, and the lead screw nut is fixed to the upper end of the lower end face tool apron. The servo adjustable tool can adapt to machining of brake disc parts with different specifications andsizes, the machining demands of the brake disc parts with the various specifications can be met, the production efficiency is improved, and the machining cost is reduced.