The invention discloses a method for preparing TiO2 (B) nano wires with high specific surface area. The method comprises the following steps of: preparing potassium titanate nano wires in a concentrated potassium hydroxide solution by using titanium oxide powder and adopting a hydrothermal or heating method, washing, performing acid exchange and secondary hydrothermal conversion, controlling the acid concentration and the reaction temperature of the hydrothermal reaction, and thus obtaining a large quantity of TiO2 (B) nano wires with the high specific surface. The prepared TiO2 (B) nano wires with the high specific surface have a good application prospect in the fields of lithium ion batteries, water treatment, sensors, sensitized solar cells and the like. Particularly, the TiO2 (B) nano wires applied to a cathode material for the lithium ion batteries have large capacity and can still keep large capacity at a high charge/discharge rate.