Adjustable precision boring tool holder

The utility model discloses an adjustable precision boring tool holder, in particular to a micro-adjusting tool holder of directly precision boring after rough boring, belonging to the boring apparatus technical field. A tool bar is connected with a clamp housing which is drilled and tapped, and is fixed with a clamp bolt. a round housing of a micro-adjusting inserting into the clamp housing is fastened by the clamp bolt; one side of the micro-adjusting is provided with a micro-adjusting handle, which is blocked on the micro-adjusting to radial rotate, the micro-adjusting handle is connected with an inner spindle of the micro-adjusting, which is connected with an outer spindle of the micro-adjusting by a micro-adjusting thread, the micro-adjusting handle can be twisted to fine adjust the outer spindle axial moving, the end head of the outer spindle of the micro-adjusting is connected with a tool bit base, which is placed with a pad of the tool bit, and the tool bit lays on the pad of the tool bit, a binding bolt of the tool bit is tightening on the pad of the tool bit, the tool bar is fixed on a tool rest to transverse alignment while precision boring, the micro-adjusting handle is twisted according to processing quantity, so that the outer spindle of the micro-adjusting drives the tool bit base and the tool bit moving axial, and the micro-boring is fulfilled.