X-ray diffraction (XRD) and Photoluminescence (PL) spectra for a series of high phosphorus compositional GaN_ 1-x P_ x films grown by means of light-radiation heating,low-pressure metal-organic chemical vapor deposition have been investigated. Photoluminescence spectra for GaN_ 1-x P_ x layers with P/N composition ratios of 15%,11% and 3% show the red-shifts of 100 meV,78 meV and 73 meV,respectively,from that of GaN due to a large bowing of band gap energy. X-ray diffraction results show that (0002) peaks of GaN1-xPx samples have shifted to smaller angles compared with that of an undoped GaN sample, and the linewidth of the (0002) peak becomes broader with increasing P composition in the samples, indicating that the crystal lattice distortion is produced due to the P incorporation into the GaN host lattice. Not peak related to GaP is observed in X-ray diffraction and photoluminescence spectra, which indicates that the phase separationb etween GaN and GaP has not occurred in our GaN1-xPx samples.