A saturation adjustment method is disclosed for compensating over-saturation adjustment. The saturation adjustment method includes: adjusting a first full-scale saturation corresponding to a hue of a color wheel to become a second full-scale saturation wherein the second full-scale saturation is greater than the first full-scale saturation; setting a critical saturation corresponding to the hue based on the first and second full-scale saturations; and adjusting a first saturation within a range between the critical and second full-scale saturations corresponding to the hue to become a second saturation based on the first full-scale, second full-scale and critical saturations. Furthermore, disclosed is a color adjustment system essentially including a saturation adjuster for adjusting the first saturation greater than the critical full-scale saturation to become the second saturation based on an adjusted full-scale saturation and the critical saturation.