The tetracycline (TC) in water has led to serious concern. Graphitic carbon nitride (g-C 3 N 4 ) photocatalysts were produced via copolymerization of mono-benzene ring-mediated precursors (urea, melamine, and dicyandiamide) involving salicylic acid (SA) for TC degradation. The SA-modi ed g-C 3 N 4 samples showed improved visible-light absorbance, transfer and separation of photogenerated electrons, and prospective photocatalytic application in TC degradation. As a result, the optimal SA-modi ed g-C 3 N 4 (2 wt% of SA) using urea (CNU-SA-2) showed 2 times higher TC degradation than that of pristine g-C 3 N 4 .The process of TC degradation was evaluated by the reduction of antibacterial activity and extensively studied by varying the types of TC, initial pH values, co-existing anions, and natural organic materials. In addition, the catalyst could be reused for at least four cycles, indicating good reusability. The main active species were revealed to be h + and •O 2 − by scavenging experiments and electron spin resonance. The CNU-SA-2 photocatalyst and TC intermediates during degradation had no adverse impact on zebra sh embryos. This work could provide a design strategy and a perspective on the practical application of g-C 3 N 4 -based photocatalysts for the treatment of wastewater containing antibiotics.