Phosphorus-based anode materials have a high theoretical capacity and a medium redox potential, and the related raw materials have some advantages in reserves and costs, thus having promising application prospects in sodium and lithium-ion battery anode materials. However, red phosphorus has a fast decay rate of electrochemical activity and a poor cycling performance due to the extremely low electronic conductivity and excessive volume expansion, while black phosphorus conductivity can reach 105 S/m, and its dense structure leads to a poor intrinsic rate performance, thus restricting the practical application of elemental phosphorus as an anode material. A unique metal phosphorus-rich phosphides MPx (x≥2) can be formed by introducing a small amount of metal elements into elemental phosphorus. The electronic conductivity of metal phosphorus-rich phosphides MPx can be greatly improved via metal element electron injection, and a relatively empty crystal structure can be formed to provide faster reaction kinetics and effectively inhibit volume expansion. Therefore, metal phosphorus-rich phosphides MPx with a high capacity and superior electron/ion transport characteristics is a potential sodium and lithium-ion battery anode material. This review mainly represented the composition and structural characteristics of metal phosphorus-rich phosphides, focusing on the latest progress in the energy storage mechanism and modification strategy of metal phosphorus-rich phosphides.