Environment-friendly nano-catalysts capable of activating peroxymonosulfate(PMS)have received increasing attention recently.Nevertheless,traditional nano-catalysts are generally well dispersed and difficult to be separated from reaction system,so it is particularly im-portant to develop nano-catalysts with both good catalytic activity and excellent recycling efficiency.In this work,magnetically recoverable Fe3O4-modified ternary CoFeCu-layered double hydroxides(Fe3O4/CoFeCu-LDHs)was prepared by a simple co-precipitation method and initially applied to activate PMS for the degradation of Rhodamine B(RhB).X-ray diffrac-tion(XRD),fourier transform infrared spectrometer(FT-IR),scanning electron microscope(SEM),transmission electron microscopy(TEM),Brunauer-Emmett-Teller method(BET),and vibrating sample magnetometer(VSM)were applied to characterize morphology,structure,specific surface area and magnetism.In addition,the effects of several key parameters were evaluated.The Fe3O4/CoFeCu-LDHs exhibited high catalytic activity,and RhB degradation efficiency could reach 100％within 20 min by adding 0.2 g/L of catalyst and 1 mmol/L of PMS into 50 mg/L of RhB solution under a wide pH condition(3.0-7.0).Notably,the Fe3O4/CoFeCu-LDHs showed good super-paramagnetism and excellent stability,which could be effectively and quickly recovered under magnetic condition,and the degradation efficiency after ten cy-cles could still maintain 98.95％.Both radicals quenching tests and electron spin resonance(ESR)identified both HO·and SO4·-were involved and SO4·-played a dominant role on the RhB degradation.Finally,the chemical states of the sample\'s surface elements were mea-sured by X-ray photoelectron spectroscopy(XPS),and the possible activation mechanism in Fe3O4/CoFeCu-LDHs/PMS system was proposed according to comprehensive analysis.