The invention relates to a projection system, which comprises a light emitting device, a light splitting device, a spatial light modulator and an image processing device, wherein the light emitting device provides first light and second light subjected to time series emergence; the light splitting device splits the first light into first primary color light and second primary color light, splits the second light into two paths of third primary color light, enables the first primary color light to be emitted along a first light path in a first time series, enables the second primary color lightto be emitted along a second light path, enables the first primary color light to be emitted along the second light path in a second time series, enables the second primary color light to be emittedalong the first light path, and enable two paths of third primary color light to be independently emitted along the first light path and the second light path in a third time series; the spatial lightmodulator comprises a first area and a second area, wherein the primary color light emitted along the first light path enters the first area, and the primary color light emitted along the second light path enters the second area; and the image processing device divides an image signal to be output into two groups by corresponding to the first area and the second area, and changes the series of at least one group to match with the time series of the primary color light received by the corresponding area. By use of the projection system, light loss during light splitting can be avoided, and the use ratio of light energy is improved.