NOVELTY - A load gold molecular sieve based catalyst is converted to isobutane by preprocessing silica rich zeolite vector; preparing load gold catalyst via deposition precipitation method under a negative pressure condition by carrying out negative pressure degasification purification treatment for the preprocessed hydrogen zeolite carrier at 20-90 degrees C for 0.5-12 hours and at - 0.01 to - 0.1 MPa; and carrying out n-butane isomerization to produce isobutane on fixed bed reactor.    USE - Method for converting load gold molecular sieve based catalyst to iso-butane (claimed).    ADVANTAGE - The method uses load gold catalyst beneficial for inner and outer surfaces and porous channels of the molecular sieve to purify via a deposition precipitation method under a negative pressure condition, thus enabling gold to easily enter into the porous channels of the molecular sieve to reach high dispersion.    DETAILED DESCRIPTION - Converting load gold molecular sieve based catalyst to isobutane comprises:    (A) preprocessing silica rich zeolite carrier by (a) baking silica rich zeolite carrier for 3-8 hours at 400-600 degrees C, a ratio of silicate to aluminum of the silica rich zeolite being more than 10; (b) carrying out ion exchange process for the baked zeolite via 0.05-1 mol/L of ammonium nitrate, ammonium chloride or ammonium carbonate, a solid volume ratio of ammonium salt solution and zeolite solution being 3:1-10:1, for 0.2-100 hours, controlling sodium ion content to be less than 1%, using deionized water to wash, and obtaining hydrogen zeolite via drying at 80-200 degrees C for 1-100 hours, and baking for 3-8 hours at 400-600 degrees C; and (b) carrying out acid broaching process for the hydrogen zeolite via hydrochloric acid, nitric acid or citric acid; washing with deionized water, and obtaining the carrier via drying;    (B) preparing load gold catalyst via deposition precipitation method under a negative pressure condition by (d) carrying out negative pressure degasification purification treatment for the preprocessed hydrogen zeolite carrier at 20-90 degrees C for 0.5-12 hours and at - 0.01 to - 0.1 MPa; keeping the temperature and negative pressure state while stirring, using gold precursor to in contact with the carrier, and adding precipitator into mixture to react the load gold by the negative pressure deposition precipitation reaction for 5-100 hours; and (e) performing solid-liquid separation, washing for removing chlorine ion using deionized water, and drying and baking; and    (C) carrying out n-butane isomerization to produce iso-butane on fixed bed reactor at 150-600 degrees C for 0.3-3 MPa; carrying out n-butane isomerization to produce isobutane on a movable reactor at 150-600 degrees C and 0.1-0.5 MPa; and carrying out n-butane isomerization to produce iso-butane on fluid bed reactor at 150-600 degrees C and 0.1-0.3 MPa.