The invention relates to a low-resistance electrode, a preparation method and application thereof in carbon-based perovskite solar cells. The electrode is of a double-layer composite carbon layer structure formed by a planar carbon layer and a carbon finger or carbon network structure layer, wherein the planar carbon layer is of a planar structure, and the carbon finger or carbon network structure layer is of a carbon finger or carbon network structure; the carbon finger or carbon network structure layer is arranged on the planar carbon layer, and the coverage rate is not more than 80 %. The preparation method comprises the following steps: (1) preparing low-resistance carbon paste; (2) establishing a working curve between carbon layer thickness and square resistance; (3) determining an appropriate thickness of the double-layer composite carbon layer structure; (4) preparing the planar carbon layer; (5) preparing the low-resistance carbon finger or carbon network structure layer. The low-resistance electrode is used on the void free carbon-based perovskite solar cells. Compared with the prior art, the low-resistance electrode provided by the invention has the advantages of improving the photoelectric conversion efficiency and stability of the cells, reducing cost and simplifying process and the like.