A lanthanide coordination polymer (Tb/GMP/Ag)-based pH fluorescence probe was designed for the first time. Tb/GMP/Ag possesses strong luminescence and excellent water-dispersion due to using hydrosoluble biomolecule of GMP as organic ligand and Ag+ as sensitizer. High sensitivity and selectivity for OH− were obtained based on time-resolved technology and the specificity between Ag+ in Tb/GMP/Ag and OH−.