A system and method for dynamically adjusting a color gamut of a display system, and a display system are provided. The display system includes a light source system and an imaging system. The light source system includes an excitation light source and a narrow-spectrum primary-light source. The imaging system includes a spatial light modulation device and the system for dynamically adjusting the color gamut. The excitation light source emits excitation light which is processed to output at least one broad-spectrum primary light. The narrow-spectrum primary light source outputs narrow-spectrum primary light. The narrow-spectrum primary light and the broad-spectrum primary light are combined and then output to the imaging system. The brightness of light emitted by the excitation light source and the narrow-spectrum primary light source is adjusted.