With the rapid development of industrialization and technology, antibiotic wastewaterEnergy Environmental Protectionpollution has become a serious environmental problem facing human beings. Conventional physical andbiological techniques are often ineffective in removing antibiotic residues from water. Sulfate radical-based advanced oxidation processes (SR-AOPs) are considered among the most promising methods forantibiotic removal in practical applications due to their strong degradation performance and fast reactionrates. In this study, the NHCl-modified Cu/N co-doped biochar (Cu-N) was prepared via a two-stepcalcination process and used to activate peroxymonosulfate (PMS) for the degradation of tetracyclinehydrochloride (TCH) in water. This modification was designed to overcome the limitations of pristinebiochar (BC), which lacks metal active sites and has inherent physicochemical properties that areinsufficient for handling increasingly complex antibiotic wastewater. Compared with BC, Cu-N, andCu-N, Cu-N exhibited the best defect structure and morphology characteristics. The high-temperaturemodification using NHCl facilitated more effective Cu and N doping onto the biochar surface,providing a greater abundance of active sites and N-containing functional groups. Degradationexperiments demonstrated that Cu-N exhibited superior PMS activation efficiency compared with BC,Cu-N and Cu-N. After a 60-minute degradation experiment, the TCH degradation efficiency reachedapproximately 78.95%, representing a 29.09% increase compared to pristine BC, with minimalcontribution from adsorption. In the analysis of influencing factors, the effect of acid washing wasnegligible, and the Cu-N/PMS system functioned effectively within a broad pH range (3 to 9). Cu-Nalso exhibited the fastest reaction rate (k = 0.025 88 min), as calculated using the first-order reactionkinetic constant. When [TCH] = 10 mg/L, the most economical experimental conditions weredetermined to be [Cu-N] = 0.2 g/L, [PMS] = 1.0 mmol/L, and pH = 7. Further investigations confirmedthat the Cu-N/PMS system possessed good anti-interference capability and high practical applicability,maintaining high degradation activity even in the presence of various anions and humic acids.Moreover, Cu-N demonstrated removal efficiency for other common pollutants, including RhodamineB (RhB), Methylene Blue (MB), Ciprofloxacin (CIP), and Carbamazepine (CBZ), indicating its broadapplicability. Radical quenching experiments revealed that the free radical pathway was nearly inactivein the Cu-N/PMS/TCH system, while non-radical mechanisms, primarily singlet oxygen O and high-valence Cu(Ⅲ) species, dominated TCH degradation. This work provides valuable insights for therational design of modified biochar and its application in PMS activation for antibiotic degradation.