Recent progress of molecular thermodynamics for chain-like molecule systems in China mainly at East China University of Science and Technology (ECUST) and at Beijing University of Chemical Technology (BUCT) is presented. Molecular simulation results of phase equilibria for chains on both lattice and free space by a configurational-bias vaporization method are summarized. Molecular thermodynamic models based on both cell and lattice approaches and corresponding group-contribution methods are developed that can be successfully used to describe phase behavior. Using cavity correlation function (CCF), an equation of state for chain-like molecule systems is derived that contains three contributions: a hard-sphere-chain reference, a square-well perturbation term and an association term. Numerous illustration examples for practical VLE and LLE calculations are shown. Extension to polyelectrolytes is also presented that shows good results for osmotic pressures in comparison with experimental results.