NOVELTY - A palladium and niobium doped organic-inorganic hybrid silicon dioxide film preparing method involves preparing palladium, niobium-hybrid silicon dioxide sol by mixing silicone with lower alcohol, adding catalyst, placing in water bath to obtain hybrid silicon dioxide sol. The removed hybrid silicon dioxide sol is placed in ice salt bath, lower alcohol solution of niobium n-butoxide, and siloxane, catalyst is added to obtain niobium-hybrid silicon dioxide sol. Palladium salt is mixed with a solvent to obtain mixed solution, followed by diluting palladium salt solution, heating and cooling.    USE - Method for preparing palladium and niobium doped organic-inorganic hybrid silicon dioxide film for purifying hydrogen, carbon dioxide and methane.    DETAILED DESCRIPTION - A palladium and niobium doped organic-inorganic hybrid silicon dioxide film preparing method involves preparing palladium, niobium-hybrid silicon dioxide sol by mixing silicone with lower alcohol at volume ratio of 0.1-1:1, adding catalyst, placing in water bath at 40-90 degrees C for 1-3 hours to obtain hybrid silicon dioxide sol. The removed hybrid silicon dioxide sol is placed in an ice salt bath, lower alcohol solution of niobium n-butoxide, and siloxane at ratio of 0.1-1.5:1, catalyst is added continuously in constant temperature water bath at 40-90 degrees C for 1-3 hours, to obtain niobium-hybrid silicon dioxide sol. Palladium salt is mixed with a solvent to obtain mixed solution at concentration of 2-6 mol/l, placed at 20-60 degrees C constant temperature bath for 20-60 minutes, and the palladium salt solution is mixed with a lower alcohol to obtain a palladium salt solution followed by diluting palladium salt solution with low carbon alcohol at 20-60 degrees C to obtain palladium salt diluent, controlling Nb-hybrid silicon dioxide sol volume ratio of 2-10:1, clarification of Pd, Nb-hybrid SiO2 sol, sintering dried film Pd, Nb-hybrid silicon dioxide sol coating on the support surface, drying liquid coating film, mixing H2 with an inert gas atmosphere, heating at 300-600 degrees C for 1-10 hours after natural cooling to obtain finished product.