The invention discloses a preparation method for a Ga-doped ZnO nanometer material, and belongs to the technical field of preparation of nanometer materials. The preparation method is characterized by comprising the following steps of: dissolving zinc nitrate and gallium nitrate into de-ionized water, wherein the molar ratio of the zinc nitrate to the gallium nitrate is 1:0.01 to 1:0.1, and a PH value is controlled within the range of 9 to 11; performing ultrasonic treatment on the mixed solution for 30 minutes to obtain a reaction precursor solution; ultrasonically washing a fluorine-doped tin oxide (FTO) conductive glass substrate by using acetone, absolute ethanol, isopropyl alcohol and the de-ionized water, and drying the washed FTO conductive glass substrate; placing the treated glass substrate in the prepared reaction precursor solution, and sealing the reaction precursor solution and preserving the heat; and taking the glass substrate out, flushing the glass substrate by using the de-ionized water, and drying the glass substrate to obtain the glass substrate to which the Ga-doped ZnO nanometer material is attached. The preparation method is low in reaction temperature and low in cost, and simple equipment is used; and in addition, the prepared product has a fluffy and porous surface, high porosity and high electric conductivity, and is applicable to devices such as dye sensitized solar cells and the like.