The invention discloses a preparation method and application of a TiO2 nanorod array thin-film electrode material. The method comprises the following steps: soaking a pure titanium sheet in a HCl solution or H2SO4 solution with the concentration of 8-10mmol/L for 12-24h under normal temperature and normal pressure conditions, cleaning the pure titanium sheet by using deionized water after the reaction is ended until the PH value is 7, drying at the temperature of 70-110 DEG C, calcining at the temperature of 400-600 DEG C for 1-2 hours, and thus obtaining the TiO2 nanorod array thin-film electrode material. The invention also discloses application of the TiO2 nanorod array thin-film electrode material in disease attribute miRNA related electrochemical biological sensing detectors or biological sensing devices. The TiO2 nanorod array thin film is uniform in thickness, controllable in shape, firm in structure and simple in electrode preparation process, adhesion of an adhesive is not needed, and standard mass production is easily realized.