This application discloses a perovskite solar cell having a hole transport layer with comb fiber structures and a preparation method thereof. The perovskite solar cell comprises a transparent electrode layer and a hole transport layer with comb fiber structures formed on the transparent electrode layer. The hole transport layer with comb fiber structures is made of a polythiophene-based polymer hole transport material. The preparation method comprises the following steps: depositing an oxidant on a transparent electrode layer; contacting a solution containing a strongly polar acid and a thiophene-based hole transport material monomer with the oxidant and reacting to obtain a hole transport layer with comb fiber structures; and synthesizing a perovskite absorption layer on the hole transport layer with comb fiber structures, and then providing an electron transport layer and an electrode layer on the perovskite absorption layer in sequence. The solar cell has a hole transport layer with uniform and high-density comb fiber structures, resulting in an increased contact area between the hole transport layer and the absorption layer. The hole transport layer is of comb fiber structures, which increase the contact area between the hole transport layer and the absorption layer.