The crystallization of N,N-di(n-cetyl)quinacridone (DCQA) gives two crystalline polymorphs A and B. It is found that crystalline polymorphs A and B adopt remarkable different packing structures. The form A crystal is characterized by the strong intermolecular π⋯π interaction and C–H⋯O interaction. The form B crystal displays an intermolecular C–H⋯π interaction and hydrogen bonding interaction feature. In form B, every quinacridone core is sandwiched by two alkyl chains from two adjacent DCQA molecules. The photoluminescent (PL) spectra of two polymorphs in solution and in the solid state were reported. The PL spectra of DCQA in solution exhibit concentration-dependent property. The emission spectrum of form A displayed an obvious red shift compared to that of form B. The studies of the single-crystal structures and the solid-state emission spectra of the two polymorphs demonstrated that the molecular packing is the critical element determining the solid-state emission.