The invention discloses a method for preparing a carbon nitride modified titanium dioxide nano-tube photo-anode material. The method comprises the steps of preparing a titanium dioxide photo-nano-tube anode by using an anodic oxidation method; preparing carbon nitride by calcining a cyanuric acid and melamine mixture; uniformly spreading the cyanuric acid and melamine mixture between two pieces of anodized titanium dioxide; and carrying out calcining in nitrogen to make carbon nitride grow in the wall and the diameter of a titanium dioxide nano-tube to obtain a carbon nitride coated titanium dioxide nano-tube photo-anode of which the photoelectric properties are improved. The method is simple in preparation and capable of achieving reaction control easily and preparing a carbon nitride coated titanium dioxide nano-tube, and the coating effect of carbon nitride on the titanium dioxide nano-tube is relatively good.