NOVELTY - Preparation of simultaneously etched and tungsten-doped titanium dioxide nano-wire array, involves: (1) mixing water and concentrated acid, adding titanium source, stirring reaction mixture, then transferring to reaction vessel into substrate face down into inner vessel, at 140-180 degrees C reaction condition for 4-20 hours; (2) flushing the step (1) obtained product, drying at 450-550 degrees C in air atmosphere; and (3) placing pure titanium dioxide nano-wire array obtained in step (2) in hydroxylamine hydrochloride, sodium sulfide and sodium tungstate water solution, and reacting at 150-200 degrees C.    USE - For preparation of simultaneously etched and tungsten-doped titanium dioxide nano-wire array useful in the photolysis of water using solar energy to produce hydrogen and photocurrent; and in the preparation of solar energy battery (claimed).    ADVANTAGE - The preparation method utilizes titanium dioxide (TiO2) nanowires during etching under weakly alkaline conditions to achieve efficient tungsten doping; improves the efficiency of the solar cell light absorption, to achieve an efficient photolysis of water to produce hydrogen and photoelectric conversion photocurrent step process; has wide range of sources of raw materials; is simple, inexpensive and environment-friendly; and is good for popularization.    DETAILED DESCRIPTION - Preparation of simultaneously etched and tungsten-doped titanium dioxide nano-wire array, involves: (1) mixing water and concentrated acid for 0.1-0.5 hours, then adding titanium source, stirring reaction mixture for 5-10 minutes, then transferring to reaction vessel into the substrate face down into the inner vessel, at 140-180 degrees C reaction condition for 4-20 hours; (2) flushing the step (1) obtained product, drying at 450-550 degrees C in air atmosphere for 1-2 hours to obtain pure titanium dioxide nano-wire array; and (3) placing pure titanium dioxide nano-wire array obtained in step (2) in hydroxylamine hydrochloride, sodium sulfide and sodium tungstate water solution, and reacting at 150-200 degrees C for 2-10 hours to obtain simultaneously etched and tungsten-doped titanium dioxide nano-wire array.