The group contribution (GC) approach was incorporated into the simplified hole theory equation of state (SHT EOS) for polymers, solvents, and polymer-solvent solutions, proposed by the authors previously. The group parameters for polymers and solvents were obtained for the description of the PVT relationship for 59 polymers and 59 solvents with remarkably better prediction accuracy, compared with the GC-Flory and GCLF EOSs. Furthermore, a binary group interaction parameter matrix containing 110 parameters were recommended for the prediction of weight fraction activity coefficients (WFACs) for polymer-solvent solutions. The prediction results for 96 data sets indicate that the GCSHT EOS is superior to the GCLF EOS with the grand average 6.7% against 14.5% for the latter.