The invention discloses a vertical lathe grinding device. A grinding function is developed on the basis of the original vertical lathe turning machining, so that the aim that the device has a plurality of functions is fulfilled. The device is characterized in that: a sliding post vertically arranged on a vertical lathe has a hollow structure; a rotating shaft is vertically arranged in a cavity ofthe hollow structure of the sliding post; the rotating shaft and the sliding post are rotationally supported through a bearing; a servo motor is arranged at the upper end of the rotating shaft, and is in transmission connection with the rotating shaft; the rotating shaft also has a hollow structure; a linear driving mechanism and a grasping device are arranged in a cavity of the hollow structure of the rotating shaft; a cutter frame is arranged at the bottom of the cavity of the hollow structure of the rotating shaft; and a grinding wheel is arranged at the lowest end of the cutter frame.