Abstract: The shortage of water resources and the increase of water demand for human production and life have made the topic of wastewater purification and treatment hot. The advanced oxidation process has become a proven method to treat wastewater because it is efficient, environmentally friendly and free of secondary pollution. The most representative ones are photocatalytic technology and Fenton technology. Three different morphologies of ZnFe₂O₄ nanocrystals, namely microspherical (ZFO-1), hollow spherical (ZFO-2) and orthohexagonal (ZFO-3), were prepared by hydrothermal and calcination methods by adjusting the process parameters. The microstructure, morphology, elemental composition and photoelectrochemical properties of the samples were characterized by XRD, SEM, HRTEM, UV-vis, electrochemical impedance spectroscopy (EIS) and transient photocurrent response tests. Furthermore, the ZnFe₂O₄ nanocrystal photo-Fenton properties were derived from the degradation of rhodamine B (RhB). The results show that all three prepared ZnFe₂O₄ nanocrystals have cubic spinel structure and good crystallinity. ZFO-2 exhibits excellent visible light absorption and the narrowest band gap with red-shift phenomenon. EIS tests show that ZFO-2 has the lowest internal resistance to transfer and the highest transient photocurrent, with excellent migration and separation of photogenerated carriers. The photo-Fenton degradation efficiencies of ZFO-1, ZFO-2 and ZFO-3 catalysts are 88.2%, 97.6% and 48.1% in order, indicating good degradation performance. The comprehensive obtained, ZFO-2 has excellent photodegradation performance. And the possible catalytic mechanism of photo-Fenton degradation of RhB was discussed.