A kind of phononic crystal shaft with piezoelectric ceramic circular rings is proposed in this paper. Based on the wave equation, the propagating characteristics of torsional wave are calculated by the transfer matrix method. The torsional wave band structures of infinite piezoelectric phononic crystal shaft (PPC shaft) and transmission curves of finite PPC shaft are analyzed, then simulations are carried out to verify the theoretical results by using ANSYS software. Furthermore, the effects of outer active control on the torsional wave band gaps are considered by changing feedback control gains. The influences of the ratios of length and cross-sectional area on the band gaps are also discussed in detail. Results show that there exist band gaps of torsional vibration in this special PPC shaft and the width together with the position of the band gaps can be adjusted effectively by varying structural parameters and outer active control gains.