We report the synthesis and characterization of a series of compounds with general composition Y1-xPb2+1.5xF7, (-1.33 less than or equal to x less than or equal to 1.0) to establish a detailed phase relation in the PbF2-YF3 system. The solid solubility limit of YF3 in PbF2 lattice, under short annealed and slow cooled conditions, is represented as Y0.7Pb2.45F7, (i.e., about 22 mol % of YF3). The existence of a rhombohedral phase with the composition Y1.2Pb1.70F7 was seen beyond the saturated solubility limit. A new phase with an orthorhombic unit cell was identified within the narrow range of compositions Y1.3Pb1.55F7 and Y1.4Pb1.40F7. Subsequent compositions, towards YF3 side, exist as a mixture of the orthorhombic phase and leftover beta -YF3. It was also observed that in the present experimental conditions no PbF2 could be incorporated in the lattice of beta -YF3.