The invention discloses a positioning method for liquefied natural gas (LNG) storage tank leakage. The method comprises the steps of: (a) installing 4 sets of bulbs on the outer wall of the storage tank to serve as reference points; (b) installing four infrared thermal imagers outside the storage tank; (c) turning on the eight bulbs, and starting the four infrared thermal imagers to conduct infrared imaging scanning on the LNG storage tank so as to form a temperature distribution infrared image, and then transmitting the temperature distribution infrared image into a computer to undergo analytical processing; (d) intercepting a cooling image part having local continuous cooling change from an overall outer wall temperature distribution image of the LNG storage tank, and making an isothermal line according to the cooling image part; and (e) arbitrarily taking N points from a control temperature located isothermal line, figuring out storage tank leakage corresponding points on the storage tank outer wall, connecting the all storage tank leakage corresponding points to form a connected line surrounding an area, i.e. the actual storage tank leakage area. By means of the method provided by the invention, the LNG storage tank work reliability can be improved.