Due to the tight coupling between ocean acidity and atmospheric concentrations of the greenhouse gas CO2, reconstruction of the former is one of the major goals in paleoclimatology. Given that instrumental records of seawater pH exceeding a single decade are not yet available, the boron isotopic composition of marine carbonates currently offers the only practical means to determine paleo-seawater through time. The boron isotope ratios are best measured by thermal ionization mass spectrometry (TIMS).The boron isotope-pH proxy is founded on a theoretical model of carbonate δ11B variation with pH that assumes that the boron isotopic composition of marine carbonates mirrors the boron isotopic composition of borate in seawater. Quantified, reconstruction of ancient ocean pH requires a precise definition of α (the Equilibrium isotope fractionation factor between borate and boric acid) and pKB (the apparent dissociation constant of boric acid) and further knowledge of δ11B of ancient seawater, which is impacted by the rate of continental erosion. Complications aside, boron isotopes remain a powerful tool in the reconstruction of past seawater pH, however, various aspects of these parameters require rigorous evaluation. Therefore, given our current understanding, great care should be taken when interpreting long-term trends in δ11B of marine carbonate when the ultimate goal is to reconstruct ocean pH and ancient atmospheric carbon dioxide levels. The paleo-pH reconstructions by δ11B of marine carbonate show a higher pH in glacial ocean which is consistent with lower atmospheric carbon dioxide concentrations recorded ice cores and demonstrate the coupling between surface ocean chemistry and the atmosphere, allowing for quantitative estimation of atmospheric p(CO2) beyond the reach of ice cores. However, high resolution δ11B ratios of corals show rapid change of paleo-pH at decadal-millennial timescale indicating p(CO2) between ocean and atmosphere may not be always in equilibrium and there are other forcing accounting for variability of ocean pH. Improvement the model of the boron isotope-pH proxy, high resolution paleo-pH reconstruction and relationships between ocean pH globe carbon cycling need to be pay more attention in future works of this field.