By modifying the salicylic-acid moiety with electron-withdrawing or –donating groups, three new terbium complexes(L~Ⅰ·Tb, L~(Ⅱ)·Tb, L·~(Ⅲ)Tb) based on tripodal carboxylate ligands were synthesized. Due to different pull-push electronic effects of ligands, the fluorescence intensities of these terbium complexes significantly varied, that is: L~(Ⅱ)·Tb > L~(Ⅲ)·Tb > L~Ⅰ·Tb. Meanwhile, the characteristic peaks at 492 nm(~5D_4→~7F_6) and 547 nm(~5 D_4→~7F_5) showed “Off–On–Off” fluorescence response to various p H conditions,which indicated that all of them can be used as the highly sensitive pH fluorescent probes. Notably, using L~(Ⅱ)·Tb with the best fluorescence performance as a probe, some patients’ urine samples can be easily monitored through the response triggered by pH value. Therefore, L~(Ⅱ)·Tb has the potential to auxiliarily diagnose some diseases in clinical practice through p H detection of routine urine test. By modifying the salicylic-acid moiety with electron-withdrawing or -donating groups, three new terbium complexes based on tripodal carboxylate ligands (L ~ Ⅰ · Tb, L ~ (Ⅱ) · Tb, L · ~ . Due to different pull-push electronic effects of ligands, the fluorescence intensities of these terbium complexes significantly varied, that is: L ~ (Ⅱ) · Tb> L ~ (Ⅲ) · Tb> L ~ Ⅰ · Tb. Meanwhile, the characteristic peaks at 492 nm (~ 5D_4 → ~ 7F_6) and 547 nm (~ 5 D_4 → ~ 7F_5) showed “Off-On-Off ” fluorescence response to various pH conditions, which indicated that all of them can be used As the highly sensitive pH fluorescent probes. Notably, using L ~ (Ⅱ) · Tb with the best fluorescence performance as a probe, some patients’ urine samples can be easily monitored through the response triggered by pH value. ) · Tb has the potential to auxiliarily diagnose some diseases in clinical practice through p H detection of routine urine test.