The invention discloses a bending forming method for a small bending radius tube. The method comprises the following steps that S1, a tube blank is filled with a solid particle medium; S2, the tube blank is put into a forming die and sealed; S3, current is applied to the tube blank, and electrifying is stopped after the temperature of the tube blank reaches an experiment required temperature; S4,the right end of the tube blank is driven to move inwards in the axial direction, the left side of the tube blank is driven to move in a tangential direction, shear-bending deformation of the tube blank occurs, and the left end of the tube blank is driven to move inwards in the axial direction; S5, when the forming size of the tube blank reaches a set value, feeding is stopped, and a formed tube is obtained; and S6, a punch is reset, the forming die is opened, the formed tube is taken out, the solid particle medium in the tube blank is removed, and the small bending radius tube is obtained. The problem of low forming limit in existing tube bending forming technologies at normal temperature can be solved, and the obtained formed tube has the characteristics such as small bending radius, high forming precision and excellent shaping performance.