The invention relates to a device for machining an axial oil hole of a grinding roll shaft of a vertical mill, which comprises a support platform, a left support plate, a right support plate, a spiral translation mechanism, a support fixing device and alignment devices, wherein spiral translation mechanism comprises a motor and a speed reducer connected with the motor; the speed reducer is connected with screws arranged in a front bearing base and a rear bearing base by shaft couplers; nuts matched with the screws are arranged on the screws; a slide plate is fixed on the nuts; the support fixing device comprises a left V-shaped base and a right V-shaped base which are fixed on the slide plate respectively; a left pressing plate is arranged on the left V-shaped base, a right pressing plate is arranged on the right V-shaped base, and the screws for fixing the left pressing plate and the right pressing plate on the slide plate are arranged on the left pressing plate and the right pressing plate respectively; the alignment devices comprise a left tip cone arranged on the same axis and a right tip cone fixed by a drill clamp; and the left tip cone is fixed on the platform by a tip cone frame. By the device, the alignment operation before the axial oil hole of the grinding roll shaft of the vertical mill is machined is simple, the alignment accuracy is high, flexible and convenient, and the machining accuracy, reliability and safety are high.