The invention discloses a lower-mounted wheel pair radial device of a wagon bogie. The lower-mounted wheel pair radial device is formed by a front auxiliary framework, a rear auxiliary framework and two crossing connecting rods in a pin joint manner. Each auxiliary framework is of a combined structure with a bearing saddle and a transverse arm connected. The connecting rods are arranged below a swing bolster to form a lower-mounted radial structure. The height of the center planes of the connecting rods is smaller than the height of the center planes of saddle faces of the bearing saddles of the auxiliary frameworks. The bearing saddles are formed by the saddle faces forming arc saddle structures and saddle connecting arms which are integrated with the saddle face structures and verticallyarranged at one ends of the saddle faces. The auxiliary frameworks are fixedly connected with the saddles through pull rivet assemblies. The radial device can adapt to traditional level brake and integrated brake devices well, universality of the bogie is effectively improved, and the technical transformation and product up-gradation of the bogie are facilitated; the radial device can be independently assembled, and the assembling manufacturability of the bogie is good; and the wheel pair radial device and other parts of the bogie can be directly separated through dismounting stop keys, the structures of other parts are not destroyed, and the maintenance difficulty is effectively reduced.