Methylene Blue (MB) is one kind of textile dye from thiazine dyes that negatively impacts humans and the environment. Therefore, it is very important to determine an effective method to decolorize it. Brown-rot fungus Gloeophyllum trabeum can decolorize MB, but its ability was still relatively low and required a long incubation time. In this study, the effect of adding the bacterium Pseudomonas aeruginosa at 2, 4, 6, 8, and 10 mL (1 mL ≈ 9.23 x 108 CFU) on the decolorization of MB by G. trabeum was investigated. The decolorization of MB by particular G. trabeum was 11.57%. The addition of 8 mL of P. aeruginosa into G. trabeum culture showed a maximum decolorization result of 93.20% in a liquid medium of PDB for 7 days incubation. These results indicated that P. aeruginosa could enhance biodecolorization of MB by G. trabeum, although not significant. Some metabolite products that resulted from MB degradation were azure A comes from the MB demethylation process, azure C derived from the demethylation process of azure A, and thionine from demethylation azure C.