The Shilu polygenetic compound Fe-Cu-Co deposit in Hainan has the characteristics of large-scale mineralization, high taste, and many associated components. As a Superior-type banded iron formation, some iron ores in Shilu deposit do not have the positive Eu anomaly characteristics that this type of iron formation should have. According to the activity of Eu elements, this paper analyzes the ore samples with negative Eu anomalies (Eu/Eu*=0.47~0.74) in Beiyi and Fengshuxia deposits, and considers that the metamorphism of high water-rock ratio at high temperature leads to the abnormal changes of Eu in ore. The trace element characteristics of magnetite and garnet in Shilu deposit were determined by LA-ICP-MS. Based on the characteristics of Ca+Al+Mn, Ti+V and other elements in magnetite, this paper holds that the Eu anomaly (Eu/Eu*=0.28~5.68) in hydrothermal magnetite is closely related to fluid properties. On the other hand, based on the REE distribution model of hydrothermal garnet (andradite) of the same period, combined with regional data, this paper thinks that the polygenetic complex Fe-Cu-Co deposit with negative Eu anomaly characteristics may have undergone shear structural deformation caused by massive granite intrusion and the transformation of the early Fe-Cu-Co ore deposit by heated basin brine (high salinity, high CO2 and alkalescence) during the transformation and enrichment period of Shilu mining area (240-210Ma), which was further enriched.