Abstract: Carbonate rocks dominate in the lower part of the first member of Shahejie Formation in the Huanghua Depression, Bohai Bay Basin. The geochemical characteristics of trace elements in Kongdian-Yangsanmu, Qijiawu and Qinan show that the content and distribution of trace elements varied in different pays, but those of Sr, Ba, V, Mn, Th, U were similar, and the contents of Ni, Pb, Zn and others tended to decrease from Qijiawu to Yangsanmu, indicating environmental changes during the diagenesis process. The B content varied (7.5-92.8)×10^-6 with an average of 42.8×10^-6 in Qijiawu, and varied (7.2-97.4)×10^-6 with an average of 45.21×10^-6 in Kongdian-Yangsanmu, indicating an alternating process of saline to fresh water environments. The Ti content varied (946-3 496)×10^-6 and averaged 2 319×10^-6 in the lower part of the first member of Shahejie Formation from Kongdian to Yangsanmu, showing nearby provenance characteristics. The V/(V+Ni) ratio indicated strong reducingenvironment in the study area, and the low Th/U ratio showed a higher salinity of lake water or the influence of seawater intrusion.