Abstract： Rare earth elements and yttrium (REY) are one of the most critical strategic resources in the world today. However, the intensive exploitation and supply of conventional rare metal deposits—primarily those associated with alkaline igneous rocks and ion-adsorption clays, have led to mounting challenges for the rare earth industry, including declining resource security and increasing environmental pressure. This situation underscores the urgent need to seek alternative rare earth resources. Sedimentary phosphate rocks and deep sea REY-rich sediments have emerged as promising alternatives. They are widely distributed, possess large reserves, and are enriched in heavy rare earth elements. In recent years, considerable research have focused on the REY resource potential and mineralization mechanism of these two deposits. They found that there are several economically valuable the mineral concentrated area, distributing globally. Several studies have established mining and utilization models and developed REY extraction strategies. In terms of the ore formation mechanism, current knowledge suggests that the enrichment of REY in deep-sea sediments and phosphorus deposits is closely tied to phosphorus-enrichment, although these deposits have certain differences in terms of occurrence form, mineralization environment, and rare earth source, etc. Sorption at mineral-solution interface along with early diagenesis, are considered as the key processes to REY enrichment. However, Most of these studies were published in the past 15 years, and their systematicness and depth still fall short. For example, despite their potential, commercial development remains constrained by technical, environmental, and economic challenges— including mining equipment limitations, ecological risks, and uncertain market revenues. As a result, large-scale industrial extraction from deep-sea sediments has yet to be realized. Additionally, REY enrichment mechanisms is poorly understood. In the future, multidisciplinary collaboration will be essential. Collaborative research involving multiple disciplines and multiple technical methods will enable more precise estimation of resource reserves and contribute to the metallogenic enrichment theories. This paper provides a comprehensive overview of recent advances in the understanding of the rare earth resource replacement potential and offers perspectives for future research directions in this field.