Photocatalytic degradation of pollutants coupled with simultaneous water splitting into solar fuel is still a challenge. Herein, Nb2O5 nanofiber coated by Cd0.5Zn0.5S nanosheets as a 2D/1D hybrid photocatalysts was constructed through a solvothermal method. In-situ irradiated X-ray photoelectron spectroscopy (in-situ XPS) analysis coupled theoretical calculations together confirmed that the electrons transferred from Cd0.5Zn0.5S to Nb2O5 driven by internal electric field (IEF) upon hybridization, further illustrating that a step-scheme (S-scheme) charge transfer path was formed in the Cd0.5Zn0.5S/Nb2O5 nanohybrids under simulated solar irradiation. As a result, optimized catalyst Cd0.5Zn0.5S/20% Nb2O5 (named as CZSNO20) exhibits the superior H2 evolution rate (94 μmol g−1h−1) coupled with simultaneous the degradation of antibiotics like ciprofloxacin and cephalexin. This work will provide a promising method for in situ preparing nanofiber-based S-scheme heterojunction photocatalysts towards multifunctional catalysis reaction.