The invention discloses a powder metallurgy synchronizer gear hub which comprises a gear hub body, an outer gear hub spline on the outer side of the gear hub body, and an inner gear hub spline on the inner side of the gear hub body. The inner gear hub spline comprises a guide section close to the press-in end of the synchronizer gear hub, and a locating section away from the press-in end of the synchronizer gear hub. The reference circle tooth thickness of the guide section is gradually increased from the press-in end of the synchronizer gear hub to the joint of the guide section and the locating section, and the reference circle tooth thickness of the guide section and the reference circle tooth thickness of the locating section are in smooth transition. The reference circle tooth thickness, at the press-in end of the synchronizer gear hub, of the guide section is smaller than the width of a reference circle tooth groove of an outer spline of a transmission shaft. It can be ensured that the powder metallurgy synchronizer gear hub is automatically kept coaxial with the outer spline of the transmission shaft when mounted on the outer spline of the transmission shaft, it is effectively avoided that the thick side faces of teeth of an inner spline at the press-in end of the synchronizer gear hub are extruded to be damaged, and meanwhile power and torque can be stably transferred.