This study developed a new analytical method called projection moving-window 2D correlation FTIR spectroscopy (Proj-MW2D) to separate the molecular motion of groups generated from different components or phases for multiphase and multicomponent polymers. The specific implementation steps for Proj-MW2D were enumerated after the theoretical derivation and algorithm research. Two types of two-component blends, poly(L-lactide)/poly(butylene succinate) and monodisperse polystyrene/monodisperse poly(ethylene-co-1-butene), were employed to validate the concept of separating the molecular motion of groups. Results showed that Proj-MW2D FTIR correlation technique successfully separated the molecular motion of the specific functional groups. Although MW2D and PCMW2D have the capacity to determine the multiple transitions of polymers, they cannot identify the origin of correlation intensity peaks without the help of other characterization methods. Proj-MW2D allows researchers to study the mechanism of the complex transition process for multiphase and multicomponent polymer systems. This method can be easily extended to three- or four-component polymers and to other spectra (e.g., Raman, X-ray, and UV).