A method for coordinate defect induction with a monocarboxylic acid to adjust pore channels of MIL-101 and synchronous phosphotungstic acid immobilization is disclosed. The monocarboxylic acid is added as an adjusting agent before coordination of an organic ligand and a metal to form a metal carbonyl cluster compound with metal ions for an MIL-101 carrier, then an insufficient amount of the organic ligand is added to replace a part of the monocarboxylic acid to form, with metal ions, MIL-101 with coordinate defects, and then concentrated hydrochloric acid and DMF are adopted to elute the unsubstituted monocarboxylic acid in the MIL-101 to form vacancies, thus achieving an objective of pore expanding. The MIL-101 is channel-adjustable, the pore size of the MIL-101 is adjusted and controlledby adjusting the length of the main chain of the monocarboxylic acid, and the degree of substitution of the organic ligand is adjusted by adjusting the ratio of the organic ligand to the monocarboxylic acid, thus adjusting and controlling the ratio of macropores to mesopores in the MIL-101.