The present disclosure provides a method of measuring a true shear viscosity profile of a molding material in a capillary and a molding system performing the same. The method includes the operations of: determining a setpoint temperature of the molding material before injecting into the capillary; obtaining an initial shear viscosity profile at the setpoint temperature with respect to a shear rate of the molding material; fitting an initial temperature profile with respect to the shear rate according to the initial shear viscosity based on Cross William-Landel-Ferry model; fitting a first shear viscosity profile and a first temperature profile with respect to the shear rate according to the initial temperature profile based on the Cross-WLF model; and setting the first shear viscosity profile as the true shear viscosity profile when a difference between the first temperature profile and the initial temperature profile is not greater than a threshold.