Embodiments of the present application relate to the field of heterojunction solar cells, and provide a heterojunction solar cell and a preparation method therefor. The heterojunction solar cell comprises a silicon substrate; a front-side passivation layer, an n-type doped layer, a front-side TCO layer, and a front-side electrode are sequentially disposed on the front side of the silicon substrate in an overlapped mode; a back-side passivation layer, a p-type doped layer, a back-side TCO layer, and a back-side electrode are sequentially disposed on the back side of the silicon substrate in an overlapped mode; the front-side TCO layer and/or the back-side TCO layer comprise/comprises at least two layers of TCO thin films, the TCO thin films of some layers are low-doped TCO thin films having a doping concentration of 0wt% to 5wt%, and the TCO thin films of some layers are high-doped TCO thin films having a doping concentration of 8wt% to 15wt%. According to the heterojunction solar cell and the preparation method therefor, the reliability of the heterojunction solar cell is effectively improved and the aging attenuation of the heterojunction solar cell is slowed down while the cost and efficiency of the cell are ensured.