To deepen the reform of undergraduate teaching, a comprehensive experiment on “the adsorption and decolorization effects of Pleurotus ostreatus strains on dyes” in the environmental microbiology experiment course is proposed. After completing the cultivation of Nameko mushroom strains in the previous experiment, the mycelia formed are weighed to carry out the dye decolorization experiment. The adsorption and decolorization process are analyzed, which involve measuring the absorbance and Zeta potential of the dye solution as well as observing color changes on the mycelial surface/cross-section. The results show that the decolorization effects of Nameko mushroom strains on different dyes are significantly different, and the removal rate for 10 mg/L BL blue dye reach 93.06%. By comparing the mycelial surface/cross-section images at different treatment times, the adsorption and diffusion processes of the dye inside the mycelia are intuitively presented. Dyes with high electronegativity are more tightly bound to the mycelia and exhibit better decolorization effects. This experimental design can not only cultivate students’ basic operational skills, but also enable students to fully understand the application of microorganisms in water treatment. It is of great significance for cultivating senior professionals with both scientific research spirit and practical ability.