NOVELTY - A lithium hydrogen titanate nanometer tube or wire is prepared by ultrasonically and then hydrothermally reacting industrial titanium dioxide and sodium hydroxide solution; then washing a product of the hydrothermal method with a diluted acid, drying the product to obtain a white and fluffy powder product which is a titanic acid nanometer tube or wire; and mixing the titanic acid nanometer tube or wire with water soluble lithium salt solution, agitating for 0.5-3 hours, and then hydrothermally reacting for 24-72 hours to obtaining the lithium hydrogen titanate nanometer tube or wire.    USE - Method, i.e. ultrasonic chemical hydrothermal method, for preparing a lithium hydrogen titanate nanometer tube or wire (claimed). The prepared tube or wire is used for an electrode material of a lithium ion battery, a supercapacitor or mixed battery, and for an electric automobile.    ADVANTAGE - The prepared lithium hydrogen titanate nanometer tube/wire has higher specific capacity, better charging and discharging performance, and circulation stability under large current and longer service life as compared with a lithium titanate nanometer tube/wire prepared by the hydrothermal method.    DETAILED DESCRIPTION - Preparation of a lithium hydrogen titanate nanometer tube or wire with high specific energy, comprises:    (A) mixing industrial titanium dioxide (2-10 g) with sodium hydroxide (NaOH) solution (70 ml) having a concentration of 7-20 mole/L, agitating for 3-5 hours, and after ultrasonically reacting for 0.5-2 hours, hydrothermally reacting for 24-100 hours, where the hydrothermal temperature is 120-200 degrees C;    (B) after finishing the reaction, washing a product of the hydrothermal method for 0.5-10 hours under the condition of 2-5 of pH value with 0.1-0.4 M of diluted acid, drying the product at 80 degrees C after vacuum filtering to obtain a white and fluffy powder product which is a titanic acid nanometer tube or wire having the formula H2TinO2n+1asteriskxH2O; and    (C) mixing the titanic acid nanometer tube or wire (1-3 g) with water soluble lithium salt solution (40 ml) containing 0.4-0.6 mole/L of lithium, agitating for 0.5-3 hours and then hydrothermally reacting for 24-72 hours in which the hydrothermal temperature for preparing the nanometer tube or wire is 120-200 degrees C, and after finishing the reaction, obtaining a lithium hydrogen titanate nanometer tube or wire having the formula Li1.81H0.19Ti2O5asteriskH2O.