A facile method for the synthesis of a Ln3+ (Eu, Tb) doped BiPO4 (BPO) nanocrystals were developed using an environment-friendly low temperature hydrothermal method assisting with phenol formaldehyde resin (PFr). Structure and surface functional groups of BPO samples were characterized by XRD and IR patterns. Morphology was studied by SEM technology also. Furthermore, doped BPO display strong red and green emissions from Eu3+ and Tb3+ ions respectively, and the BPO suspension is selectively quenched upon addition Fe3+ ions, and there is barely any interference by other metal ions, thus making the nanocrystals as a potential Fe3+ ions Fluorescent Probe, and the detection limit is below micromole level.