Carbonate cements were discovered in the Quaternary sediments at the western Qiongzhou Strait. By means of the bioclastic AMS14C isotope dating, whole- rock X- ray diffraction quantitative analysis, scanning electron microscopy, cathodoluminescence study, and whole- rock major and trace elements geochemical testing, the geochronology and genesis of rocks were studied. Results show that the diagenetic age of the carbonate cements is early to Middle Holocene, and the cements are characterized by five kinds such as isopachous fiber columnar rim cements, gravity suspension cements, horse- tooth cements, (quasi- ) coaxial accretion cements, and non- isopachous cements. The cathodoluminescence zone is widely developed and dense, and the brackish fresh water mixed zone with interaction between fresh water and sea water can be seen, indicating that the diagenetic environment includes fresh water percolation zone, brackish fresh water mixed zone, sea water percolation zone, and sea water undercurrent zone. Combined with the characteristics of the main and trace elements analyses, the carbonate cements formed in the coastal sedimentary environment, and the coastal sedimentary facies is barrier island subfacies, which belongs to beach rock. The sea level evolution history of the western Qiongzhou Strait area in the Holocene is reconstructed by combining these results with the sea level records of the Dengloujiao coral reef in the southwest of Leizhou Peninsula. There were four stages: 9.9~6.7 ka BP transgression stage, 6.7~6.2 ka BP regression stage, 6.2~4.2 ka BP transgression stage and 4.2 ka BP stable stage.