Porous fractal HKUST-1 was synthesized at low temperature (50°C) using copper nitrate trihydrate and trimellitic acid as raw materials via a methanol mixed solvent-assisted method. The microstructure of fractal HKUST-1 was characterized by XRD, SEM, XPS, FTIR, and BET analysis. The microstructure and composition of fractal HKUST-1 were characterized by XRD, SEM, XPS, FTIR, and BET analysis. Fractal HKUST-1-activated potassium persulfate (PMS) was employed for Rhodamine B (RhB) degradation. The effects of different PMS loading levels (mass of catalyst per liter of RhB solution), PMS loading (moles of PMS per liter of RhB solution), pH, and common anions in water. Key active species during the reaction were identified, and a reaction mechanism was proposed. Results indicate: Fractal HKUST-1 exhibits a layered partitioned structure, forming abundant pores with a specific surface area of 793 m2/g and an average pore diameter of 1.44 nm. At a fractal HKUST-1 dosage of 40 mg/L, PMS dosage of 25 mmol/L, and pH=5.0, the reaction system achieved a 98% degradation rate for 100 mL of 10 mg/L RhB within 30 minutes. High concentrations (70 mmol/L) of CO32? significantly inhibited RhB degradation in the reaction system. After five catalyst cycles, the RhB degradation rate in the fractal HKUST-1/PMS system remained stable. while SO42-, NO3-, and Cl- showed no significant inhibition. After five recycling cycles, the catalyst maintained a degradation rate of over 86% for Rhodamine B, demonstrating excellent stability. Furthermore, radical scavenging experiments and EPR results indicate that the primary active species in the reaction system are sulfate radicals (·SO4?) and hydroxyl radicals (·OH).