Disclosed is a pharmaceutical composition containing a bicyclo-substituted pyrazolone azo derivative or a salt thereof and a preparation method thereof. In particular, the pharmaceutical composition disclosed in the present invention contains (Z)-5-(2-hydroxyl-3-(2-(3-methyl-5-oxo-1-(5, 6, 7, 8-tetrahydronaphthalene-2-yl)-1H-pyr azol-4(5H)-ylidene)hydrazino)phenyl)furan-2-carboxylic acid or a pharmaceutically acceptable salt thereof, and at least one filler optionally selected from cellulose, microcrystalline cellulose, lactose and starch. The composition has a good stability, dissolution rate and bioavailability, and the preparation process is simple, economical and quick.