In order to solve the technical bottleneck of 1D extremely difficult bending of thinwalled aluminum tubes with large ratio of diameter to thickness, a new innerbulging and cold push bending method using polyurethanee elastic filler in block filling was proposed by comparing the advantages and disadvantages of pushbending filled with hydraulic filling, steel ball, rosin and low melting point alloy. Firstly, the optimized blanking size of 1D bending radius elbow was obtained by finite element backstepping simulation technology. Secondly, based on the optimized blanking size for Φ50 mm×1 mm in thinwalled aluminum tube with the large ratio of diameter to thickness, the innerbulging and cold push bending experiment of 1D bending radius forming was conducted, and the influence of the spherical mandrel feeding on the forming process was studied. The results show that it is feasible to optimize the blanking size by backstepping simulation technology, and the spherical mandrel feeding is the key to the innerbulging and cold push bending process. Furthermore, increasing feeding can increase the radial compressive stress, eliminate wrinkling and reduce the distortion of crosssection, while the excessive radial compressive stress can easily lead to insufficient forming. When the spherical mandrel feeding is 75°, the overall forming effect is better, the maximum wall thickness thinning rate is 6%, and the maximum crosssection distortion rate is 2.3%. Thus, the 1D bending of thinwalled tube with large ratio of diameter to thickness is successfully realized.