The invention relates to a machine column sleeved connection part dismounting device. A rack is included, and one end of the rack is provided with clamping jaws used for clamping a sleeved connectionpart, and is further provided with a first hydraulic cylinder pushing a mandrel to move relative to the sleeved connection part; and the other end of the rack is provided with a U-shaped clamping plate used for clamping the sleeved connection part, and is further provided with a second hydraulic cylinder used for pushing the mandrel to move relative to the sleeved connection part. The invention further relates to a work method of the machine column sleeved connection part dismounting device. The machine column sleeved connection part dismounting device is simple and reasonable in structural design, easy to operate, efficient, convenient and fast, and easy to use, facilitates dismounting of the sleeved connection part and has wide application prospects.