Abstract: In order to accurately determine the grade of zircon in coastal placer deposits in Hainan Is⁃ land and support resource evaluation and rational development，aiming at the systematic differences in the principles，processes and results of the two sets of technical systems of heavy sand identification method and chemical analysis method in the current industry，the lack of unified evaluation standards and the problems brought to the actual exploration work，based on the actual work experience of heavy sand miner⁃ al identification and chemical analysis of multiple coastal placer projects in Hainan Island，the analysis path and internal logic of the two core methods are systematically sorted out，the root causes of their differ⁃ ences are deeply analyzed，and the exploration and research of method optimization and joint calibration process are carried out.The results show that the heavy sand identification method is limited by artificial el⁃ utriation，mineral grain size and identification horizon，and its grade result is usually local visual value and representativeness is limited. The chemical analysis method is based on the inversion of the total amount of elements，and the results are closer to the theoretical total value. However，due to the interfer⁃ ence of zirconium and hafnium isomorphism and accessory minerals in zircon，the conversion coefficient is uncertain.By optimizing the chemical conversion formula，introducing automatic mineral analysis technolo⁃ gy，and establishing a multi-method joint calibration process of“heavy sand identification-chemical analy⁃ sis-data verification”，the system deviation between the two methods can be effectively reduced，and the comparability and reliability of grade data can be significantly improved.It is difficult for a single analysis method to take into account both efficiency and accuracy. The establishment of a multi-method collabora⁃tive quality control system is the key to improving the accuracy of the grade determination of coastal zircon placer. This method system can provide an important methodological reference for the accurate exploration and scientific evaluation of similar placer resources.

Key words: coastal placer, zircon grade, heavy sand identification method, chemical analysis method