This paper discusses the forward osmosis (FO) module model based on a previously demonstrated hemodiafilter (HDF) model, which was modified by a three-concentration-polarization (3CP) membrane model. It was verified using derivative membrane models and the optimization technique to maximize the permeate flow rate of the FO module, where the membrane properties, hollow fiber geometries and membrane orientations were the objective factors. It was clarified that the proposed FO module model comprising of the 3CP model is the most preferable one from a good agreement with the measured values. The solute permeabilities in the active layer and the support layer as the membrane properties were optimally analyzed, and the inner diameter and the length of hollow fiber were quantitatively examined.