Liquid impact forming(LIF)of double thin-walled tubes is a compound forming technology developed on the basis of tube hydroforming (THF) and stamping forming. In order to obtain better forming quality, based on the combination of hydraulic pre-forming and liquid impact forming, double thin-walled tubes forming was realized by changing the loading path of hydraulic pre-forming. The liquid impact forming principle of double thin-walled tubes and the axial feeding scheme of inner tube were introduced. The influence of axial feeding distance on the thickness distribution of double thin-walled tubes was analyzed by Dynaform finite element method, and the influence law of axial feeding distance on the formability of double thin-walled tubes was obtained.At the same time, the influence of the axial feeding distance of the inner tube on the diagonal length of the tube section was analyzed, and the influence of the axial feeding distance of the inner tube on the filling property of the double thin-walled tube was obtained. Through the study of the loading path in the hydraulic pre-forming stage, the influence of axial feeding on the forming law of double thin-walled tubes is explored, which provides theoretical and application support for the forming of double thin-walled tubes under the impact hydraulic load.