A damping shaft mechanism has a spiral shaft, spiral guide bush, a shell and blade. An external spiral structure is arranged at one end of the spiral shaft, and its core has a cone segment. An internal spiral structure is arranged in the spiral guide bush, which cooperates rotationally with the external spiral structure so that it can move along the axis relative to the spiral shaft when the spiral shaft is rotating. The two cavities change size by moving the spiral guide bush driven by the spiral shaft in the shell, and the taper on the spiral shaft makes the fit clearance between the spiral shaft and the spiral guide bush changed from maximum to minimum gradually in the damping process, so that the oil-flowing section between the two cavities changes from big to small.