The present disclosure provides a molding system for preparing a fiber-reinforced thermoplastic (FRT) composite article, including a molding machine; a mold disposed on the molding machine and having a mold cavity to be filled with a composite molding resin including a polymeric material having a plurality of fibers; a processing module configured to generate an anisotropic viscosity distribution of the composite molding resin in the mold cavity based on a molding condition for the molding machine; and a controller coupled to the computing apparatus and configured to control the molding machine with the molding condition to perform an actual molding for the composite molding resin. The anisotropic viscosity distribution of the composite molding resin is generated by taking into consideration an orientation distribution of the fibers in the composite molding resin.