Abstract: The evaluation of diagenetic alteration of marine carbonate rocks and the preservation of coeval sea water information has long been a negligible field. The examination of microscopic fabrics, cathodoluminescence images, trace elements and isotopes in the Upper Jurassic-Lower Cretaceous biohermal carbonate rock samples from the Bandaohu region, Qiangtang Basin has disclosed that these samples are characterized by low Mn and high Sr contents, low Mn/Sr ratios, and limited range of δ¹³C and δ¹⁸O values. The preservation of coeval sea water information tends to become progressively worse in the sequence of bioclastic micritic limestone→micritic grainy limestone→grainy micritic limestone→wall rocks of reefal limestone→skeletal frameworks of reefal limestone.