A flexible photo-anode of dye-sensitized solar cell and a manufacturing method thereof are provided. The method includes steps of: coating zinc oxide nanoparticles on a flexible substrate to form a seed layer; immersing the flexible substrate into a first reaction solution; heating the seed layer to form a zinc oxide nanowire array; cooling the flexible substrate to the room temperature, immersing it into the second reaction solution, and stirring the second reaction solution, so that the zinc oxide nanowire array forms a cactus-like structure. Thus, the sintering and embossing processes can be prevented.