Inverted sleeve milling tool

The invention discloses a casing inversion milling tool which comprises a shell, a piston telescopic mechanism and a blade unfolding mechanism, wherein the piston telescopic mechanism and the blade unfolding mechanism are arranged in the shell; the shell comprises an injection joint and a milling tool body which are in threaded connection, and a plurality of upper nozzles are uniformly distributed on the injection joint along the circumference; the piston telescoping mechanism comprises an upper piston mandrel, a lower piston mandrel and a floating piston, the upper piston mandrel and the lower piston mandrel are in threaded connection, the lower piston mandrel is sleeved with the floating piston, the upper piston mandrel is sleeved with a spring, and a lower nozzle is arranged at the bottom end of the lower piston mandrel; the blade unfolding mechanism comprises a blade stop sleeve arranged outside the milling tool body in a sleeving mode and a milling blade arranged in a T-shaped groove of the milling tool