The invention relates to a green-emitting rare earth phosphate phosphor precursor, green-emitting phosphor and a preparation method, wherein, the precursor comprises at least one element of Zn, Al, Li, Na, K, F elements. The chemical expression is as follows: MaLnxCeyTb1-x-y (PO4) nFb. The green-emitting rare earth phosphate phosphor precursor is prepared by a liquid phase precipitation method. The molecular formula of the green-emitting phosphor prepared by the precursor is MaLnxCeyTb1-x-y (PO4) nFb. The prepared green-emitting rare earth phosphate phosphor with regular appearance, moderate granularity is suitable for preparation of the green-emitting rare earth phosphate phosphor, has simple preparation method, and is easy to realize industrialization; the surface of the obtained green-emitting phosphor particles is smooth, the surface or the performance of the green-emitting phosphor body is greatly reduced, the reunion between the particles is decreased, and the inoxidability is increased. The size of the powder grainsize is moderate, the distribution of the granularity is narrow, and therefore, high luminous efficiency and good thermal stability are provided.