The influence of the linear and nonlinear coupling parameters on the phase synchronization of chaos between two sub-systems with primary resonance is investigated by introducing the conception of the phase for a chaotic motion. The evolution process from non-synchronized state to imperfect phase synchronization and further to perfect phase synchronization between two sub-systems with approximate primary resonance is discussed. Further investigation reveals that the transition between different phase states are related to the critical change of the Lyapunov exponents. The results show that phase synchronization between two sub-systems is enhanced with the increase of the linear coupling strength and decayed with the increase of nonlinear coupling strength.