The invention discloses a preparation method of a flexible self-doped solar cell with a high power-to-mass ratio, which has important significance for portable equipment and wearable application in the future. By adoption of a low-cost aluminum foil substrate and noncrystalline silicon (a-Si: H) prepared by a matured preparation process, a three-dimensional nano structure radial node solar cell with relatively high performance can be obtained, and is extremely high in mechanical bending performance; and the solar cell still can keep stable cell performance after being bent for multiple times.According to the technology for combining a flexible substrate and a three-dimensional nano structure are combined, combining the aluminum foil substrate and P-type doping formed by non-manmade aluminum diffusion, coating a vertical silicon nanowire, which grows under induction of a low-melting-point metal (Sn or In), with noncrystalline silicon by using a PECVD (Plasma Enhanced Chemical Vapor Deposition) thin film deposition technology to form a p-i-n structure, and taking indium tin oxide (ITO) as a transparent electrode, the intact and flexible solar cell with relatively high performance isimplemented.