Continuous variable Einstein-Podolsky-Rosen entangled optical fields can be obtained by a non-degenerate optical parametric amplifier (NOPA) operated below the threshold pump power. The optical coating parameters of optical components as input coupler, output coupler and nonlinear crystal for the two orthogonally polarized beams are different manifested as the transmissivity difference of optical coatings of the output coupler for two orthogonally polarized beams. The influence of the coating parameter difference on entanglement degree is discussed in detail based on the experimental research, which provides references for further improving the entanglement degree of entangled state light fields.