The invention discloses a preparation method for sputtering titanium dioxide nanorod arrays on a flexible substrate. The preparation method comprises the steps: flexible substrate cleaning: carrying out ultrasonic cleaning successively with acetone, ethanol and deionized water; substrate sputtering: adopting direct-current sputtering of a titanium target, wherein sputtering gas is pure argon gas and pure oxygen gas; and subsequent sputtering: continuing direct-current sputtering with the sputtering gas unchanged. The method is simple in operation, enables the thickness of the obtained nanorod arrays to be controlled by the magnetron sputtering time and the magnetron sputtering temperature, has stable product properties and uniform film forming, can be used for large-scale preparation, and is suitable for industrialized production.