The enlarged mesoporous γ-Al2O3 with significant enhanced adsorption performance towards methyl blue was synthesized via the solvent evaporation-induced self-assembly method from SB pseudoboehmite sol peptized by nitric acid using triblock copolymer P123 as structure directing agent.The effects of hydrothermal pretreatment on the structure，textural properties，morphology of the as-prepared γ-Al2O3 and the adsorption performance towards methyl blue were studied by XRD，TEM，N2 adsorption and UV-Vis techniques.The results showed that the as-prepared mesoporous γ-Al2O3 had excellent adsorption performance towards methyl blue，and the adsorption fitted Langmuir isotherm well.Its equilibrium removal capacities were 267 and 1500 mg·g-1 respectively，when it adsorbed 300 mg·L-1 methyl blue solution for 60 min，and 3000 mg·L-1 methyl blue solution for 150 min，much higher than 150 and 1080 mg·g-1 respectively of the γ-Al2O3 obtained from SB.The results also showed that hydrothermal pretreatment could increase its specific surface area and adsorption rate towards methyl blue，while having no significant effects on the uniform mesoporous structure and equilibrium removal capacity of the mesoporous γ-Al2O3.This study offers new opportunity for mesoporous alumina in adsorption of dye，such as methyl blue from wastewater.