A light source system and a display apparatus are provided. The light source system includes first and second light emitting assemblies, a wavelength conversion device, an optical assembly, and a light combining device. The first light emitting assembly generates at least one primary color light. The second light emitting assembly generates excitation light. The wavelength conversion device is at least partially disposed on the optical path of the excitation light, and used for receiving the excitation light and generating corresponding excited light. The optical assembly is disposed on the optical path of the excited light, and used for increasing the amount of optical expansion of the excited light. The light combining device is disposed on the common optical path of the primary color light and the excited light and located behind the optical assembly, and used for combining the primary color light and the excited light.