The perturbed hard-sphere-chain-association: (PHSC-AS) equation of state is applied to calculate the phase equilibrium of hydrogen bonding polymer. systems. The pure parameters of polymers are estimated by regression of pressure-volume-temperature (PVT) data of pure molten-polymer. The calculation results show a good agreement with experimental data over the wide temperature (303 to 543 K) and pressure (1 to 2001 bar) range. The calculation results for vapor-liquid equilibrium (VLE) of polymer-solvent systems also show a good accuracy with ARD error of about 4% (a total of 354). The PHSC-AS model describes well the effects of various factors on vapor pressure of hydrogen-bonding polymer solution, such as temperature, solvents with different polarity (i.e., water, alcohols, acetone, amine), and the molecular weight and molecular structure of polymer. In addition, the infinite dilution weight fraction activity coefficient (WFAC) of strongly polar solvents such as water, alcohols, and acetic acid is calculated, and the calculated results show an acceptable performance. However, the LLE calculation shows a poor performance with PHSC-AS model.