The phonon anharmonic effect caused by Sb in GaAsSb/InP heterojunction with different Sb components has been studied by measuring Raman spectra at 3~300 K. It is found that with the decrease of temperature， the peak position of long optical phonon moves to the high wave number， and the change tends to be gentle when the temperature is lower than 100K. The relationship between the optical phonon and temperature is simulated by using the three-phonon model and the four-phonon model， respectively. Compared with the experimental results， the four-phonon model agrees better with the experimental data， which indicates that the change of the temperature dependent Raman scattering peak position must consider the four-phonon anharmonic vibration. Compared with the lattice mismatched samples S1 （Sb=37.9%） and S3 （Sb=56.2%）， the phonon anharmonic obtained in the lattice matched sample S2 （Sb=47.7%） is the smallest， and the phonon lifetime in S2 is the longest by the study of phonon linearly. The phonon anharmonic effect and phonon lifetime of GaAsSb crystal lattice vibration are not only affected by the disordered scattering of the alloy， but also by the line defects and phonon scattering of the defects introduced by the mismatch with the substrate.