NOVELTY - Extracting xenon-krypton from liquid oxygen comprises: (a) sending liquid oxygen into a primary rectifying tower for rectification and separation; (b) sending the xenon-krypton concentrated solution out of a cold box; (c) sending into the cold box; (d) sending xenon-krypton two-grade concentrated solution to a three-grade rectifying tower for rectification and separation; (e) sending krypton concentrate to a four-grade rectifying tower; (f) sending xenon-containing concentrate to a five-grade rectifying tower; and (g) sending the xenon-containing fluid to a six-grade rectifying tower.    USE - The process is useful for extracting xenon-krypton from liquid oxygen (claimed).    ADVANTAGE - The process has high recovery rate of the xenon and krypton, good economic benefit, simple operation, wide application range, and high purity without pollution to the oxygen in the raw material. Moreover, it improves safety of the device, and saves investment and energy consumption of the device.    DETAILED DESCRIPTION - Extracting xenon-krypton from liquid oxygen comprises: (a) sending liquid oxygen into a primary rectifying tower for rectification and separation; where the tower pressure of the rectifying tower is controlled at 0.4 MPa, preferably 0.3 MPa; there are 4-20 column plates, preferably 10; and the temperature of the tower is controlled at -160 to -180 degrees C; obtaining oxygen at the tower top; and obtaining xenon-krypton concentrated solution at the tower bottom; (b) sending the xenon-krypton concentrated solution obtained at the tower kettle in (a) out of a cold box; decreasing the mol content of methane in the xenon-krypton concentrate to 1x 10-6 mol; and using a molecule sieve adsorption system to remove water and carbon dioxide in the xenon-krypton concentrate; (c) sending the xenon-krypton concentrated solution obtained in (b) into the cold box; sending to a two-grade rectifying tower after decreasing temperature by a heat exchanger; where the tower pressure of the rectifying tower is controlled at 0.1-0.7 MPa, preferably 0.6 MPa; there are 10-50 column plates, preferably 25; and the temperature of the tower is controlled at -110 to -160 degrees C; and obtaining oxygen at the tower top and obtaining xenon-krypton two-grade concentrated solution at the tower kettle; (d) sending xenon-krypton two-grade concentrated solution to a three-grade rectifying tower for rectification and separation; where the tower pressure of the rectifying tower is controlled at 0.1-0.7 MPa, preferably 0.5 MPa; there are 4-40 column plates, preferably 18; and the temperature of the tower is controlled at -70 to -140 degrees C; obtaining krypton concentrate at the tower top; and obtaining xenon concentrate at the tower bottom; (e) sending the krypton concentrate obtained at the tower top in (d) to a four-grade rectifying tower for rectification; where the tower pressure of the rectifying tower is controlled at 0.1-0.6 MPa, preferably 0.45 MPa; there are 4-30 column plates, preferably 15; and the temperature of the tower is controlled at -120 to -140 degrees C; and obtaining purified krypton product with mol content of not less than 99.99 % at the tower top; (f) sending xenon-containing concentrate to a five-grade rectifying tower for rectification; where the tower pressure of the rectifying tower is controlled at 0.1-0.4 MPa, preferably 0.3 MPa; there are 10-90 column plates, preferably 60; and the temperature of the tower is controlled at -80 to -110 degrees C; and obtaining xenon-containing fluid with mol content of not less than 99.99 % at the tower top; and (g) sending the xenon-containing fluid obtained at the tower top in (f) to a six-grade rectifying tower for rectification and separation; where the tower pressure of the rectifying tower is controlled at 0.1-0.4 MPa, preferably 0.25 MPa; there are 4-20 column plates, preferably 10; and the temperature of the tower is controlled at -80 to -110 degrees C; and obtaining purified xenon product by rectification.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the device used in extracting xenon-krypton from liquid oxygen.