A color gamut mapping method, comprising the steps of: determining a mapping target color gamut of an original color gamut in the same color gamut space; wherein an area of the mapping target color gamut is smaller than an area of the original color gamut; obtaining a Lab value of a color point in the original color gamut, and determining a coordinate position of the color point in a corresponding tone plane of the original color gamut according to the Lab value, wherein the coordinate position is according to a coordinate system including a horizontal axis and a vertical axis intersecting the horizontal axis; judging whether the color point is located outside a mapping target area or not according to the coordinate position; if the color point is located outside the mapping target area, determining an intersection of a horizontal line where the color point is located and a boundary of the original color gamut, and a boundary of the mapping target color gamut, wherein the horizontal line is parallel to the abscissa; determining a mapping point of the color point on the boundary of the mapping target color gamut by a ratio of an area of a pattern formed by the intersection, and an intersection of the original color gamut and one of the horizontal and vertical axes, and a difference between the area of the original color gamut and the area of the mapping target color gamut; determining a correspondence point is located on one of the horizontal and vertical axes of the pattern formed by the intersection and the intersection of the original color gamut and one of the horizontal and vertical axes according to the ratio, determining an intersection of the connection between the correspondence point and the color point and a boundary of the mapping target color gamut as a mapping point of the color point on the boundary of the mapping target color gamut; obtaining a mapping point distribution of each line segment of the boundary of the mapping target color gamut, according to the mapping point on the boundary of the mapping target color gamut; adjusting a color point mapping direction outside the mapping target area, according to the mapping point distribution of each line segment of the boundary of the mapping target color gamut, making a number of the mapping points on an unit length of the boundary of the mapping target color gamut the same; and re-converting and outputting the Lab value of the color point with the adjusted mapping direction to a RGB gray scale value; wherein a ratio of a difference between the correspondence point and a vertical coordinate distance of the mapping target color gamut, and the vertical coordinates of the mapping target color gamut is equal to the ratio. determining a mapping target color gamut of an original color gamut in the same color gamut space; wherein an area of the mapping target color gamut is smaller than an area of the original color gamut; obtaining a Lab value of a color point in the original color gamut, and determining a coordinate position of the color point in a corresponding tone plane of the original color gamut according to the Lab value, wherein the coordinate position is according to a coordinate system including a horizontal axis and a vertical axis intersecting the horizontal axis; judging whether the color point is located outside a mapping target area or not according to the coordinate position; if the color point is located outside the mapping target area, determining an intersection of a horizontal line where the color point is located and a boundary of the original color gamut, and a boundary of the mapping target color gamut, wherein the horizontal line is parallel to the abscissa; determining a mapping point of the color point on the boundary of the mapping target color gamut by a ratio of an area of a pattern formed by the intersection, and an intersection of the original color gamut and one of the horizontal and vertical axes, and a difference between the area of the original color gamut and the area of the mapping target color gamut; determining a correspondence point is located on one of the horizontal and vertical axes of the pattern formed by the intersection and the intersection of the original color gamut and one of the horizontal and vertical axes according to the ratio, determining an intersection of the connection between the correspondence point and the color point and a boundary of the mapping target color gamut as a mapping point of the color point on the boundary of the mapping target color gamut; obtaining a mapping point distribution of each line segment of the boundary of the mapping target color gamut, according to the mapping point on the boundary of the mapping target color gamut; adjusting a color point mapping direction outside the mapping target area, according to the mapping point distribution of each line segment of the boundary of the mapping target color gamut, making a number of the mapping points on an unit length of the boundary of the mapping target color gamut the same; and re-converting and outputting the Lab value of the color point with the adjusted mapping direction to a RGB gray scale value; wherein a ratio of a difference between the correspondence point and a vertical coordinate distance of the mapping target color gamut, and the vertical coordinates of the mapping target color gamut is equal to the ratio.