Abstract: In medium- and low-grade collophanite ores, complex intergrowths and similar surface properties of apatite and gangue minerals such as dolomite and quartz make it difficult for a single flotation process to remove both carbonate and silicate gangue while recovering phosphorus. Double reverse flotation sequentially removes carbonate and siliceous gangue by adjusting pulp chemistry and reagent systems at each stage, making it an important technique for processing complex, difficult-to-beneficiate collophanite ores. This paper systematically reviews the mechanisms of action of flotation reagents used in double reverse flotation and recent advances in their applications. The review covers phosphate mineral depressants and anionic collectors in the magnesium-removal stage, as well as amine-based, quaternary ammonium salt-based, amphoteric, and combined collectors in the silica-removal stage. Advances in the recovery of associated rare earth elements from phosphate ores are also summarized. Different reagents are compared in terms of selectivity, low-temperature adaptability, froth behavior, reagent consumption, and environmental impact. Current reagent systems face several limitations: insufficient selectivity due to similarities in mineral surface properties, poor low-temperature performance of fatty acid collectors, difficulties in controlling froth produced by amine collectors, high costs associated with switching between acidic and alkaline pulp conditions, inadequate coordination between the recovery of associated metal elements and phosphate ore beneficiation, and a limited range of environmentally friendly reagents. Future research should focus on optimizing double reverse flotation and metal recovery in an integrated manner throughout the entire process. Further efforts should be made to clarify the interfacial adsorption mechanisms and structure-activity relationships of flotation reagents and to integrate molecular simulation, in situ characterization, and data-driven methods into their rational design. On this basis, priority should be given to developing synergistic reagent blends with high efficiency at low temperatures, high selectivity, low environmental impact, and good compatibility among components, as well as novel silica-removal collectors suitable for acidic conditions. Research on the efficient enrichment of associated rare earth elements should also be strengthened. Future work should systematically evaluate the suitability of new reagent systems for processing complex, difficult-to-beneficiate collophanite ores and verify their operational stability under industrial conditions, taking into account overall separation selectivity, rare earth element recovery, total reagent consumption, froth controllability, and compatibility with recycled process water.