A light source system using an excitation light source and a multi-segmented color wheel device with wavelength conversion materials is disclosed. The color wheel device includes a first area having two or more first segments and a second area having two or more second segments for receiving the excitation light. The color wheel device is driven by the driving device periodically, so that a first light sequence is generated by the two or more first segments in the first working mode and a second light sequence is generated by the two or more second segments in the second working mode. The first light sequence is different from the second light sequence. The first and second working modes are switched by a switching device. The light source system may be used in image projection system generating two or more different lights sequences in different working modes.