Abstract：Diagenetic alteration and preservative evaluation of the coeval seawater information for the marine carbonate are of great significance in paleo-oceanography and sedimentology, and can especially serve as the basic work in sedimentary geochemistry and chemostratigraphy. In this paper, rock fabric observation and cathodoluminescence and trace element analysis show that most of marine carbonate rock samples from the Yangtianwo section of the Huaying Mountain in eastern Sichuan preserve original textures, show dull cathodoluminescence, and have low Mn concentrations, high Sr concentrations, and low Mn/Sr ratios, with the exception of only six samples, which are considered to have suffered from stronger diagenetic alteration, and hence could not represent the coeval seawater. Therefore, most of marine carbonate rock samples have only suffered limited diagenetic alteration, and hence contain relatively abundant original information and can represent the coeval seawater.