Hierarchical SiO2@gamma-AlOOH (Boehmite) core/sheath fibers are fabricated based on a combination of electrospinning and hydrothermal reaction. gamma-AlOOH (Boehmite) nanoplatelets are uniformly anchored on the surface of SiO2 fibers, which significantly improves the adsorption efficiency of the SiO2 fiber membrane for organic dyes and microorganisms. Compared to conventional nanoparticle adsorbents, the self-standing membrane thus prepared is highly flexible and easy to handle and retrieve, making it a promising material for water treatment. By virtue of electrospinning and a hydrothermal reaction, it provides possibilities to fabricate other functional fiber membranes with hierarchical structures, which can find potential applications in adsorption, catalysis, filtration, and other environmental remediation fields.