The stretching vibrations and band intensities in PH3 molecules were studied. The Morse oscillator parameters in the anharmonically coupled anharmonic oscillator local mode model were determined by least-squares fitting. The density functional theory method was used to calculate the ab-initio three-dimensional stretching dipole moment surfaces. The absolute band intensities were obtained and compared with the experimental data. Result predicted the intensity abnormally at the second overtone by introducing some inter-bond coupling terms to the bond dipole model.