Numerous studies reported that mixtures of Rare Earth Elements (REEs) could produce quite sensational growth-promoting effects in all categories of farm animals; but many people thought that REEs could affect human healthy. Therefore, experiments were done to understand the effects of La2O3 on red-eared sliders. The results showed that lower dose of La2O3 could probably improve the metabolism of Red-eared Slide turtle, and the higher dose of La2O3 could probably cause pathologic reaction. Lanthanum trichloride (La) could cause the Histological changes in tortoise livers. A very lower dosage of La2O3 could damage the livers of red-eared slides obviously though diversity pathway. The wild animal should be protected from harm in the RE diggings. If the RE is used or must be used as an additives in animal foods, an appropriate dose of RE was necessary, and the safety evaluation should be done.