The invention relates to a method of improving out-of-gamut color overlap mapping. The method includes: step 10, converting RGB number values of a color point P in a source gamut into L*a*b* values ofa Lab color space; step 20, determining a hue plane where the color point P is located, and further determining values of a hue angle H, color saturation C and brightness L; step 30, respectively representing intersection points of a straight line, which is defined by the color point P and a color point Lm on a brightness axis of the hue plane, and a boundary of a target color gamut and a boundary of the source color gamut as a color point PC and a color point Ps, and combining the color point Lm and a parameter alpha to determine a reference color point Pi; step 40, judging whether the colorpoint P is inside or outside a line segment |LmPi|, if the color point P is inside the line segment |LmPi|, mapping the color point P to the target color gamut, then still generating the color pointP, and entering a step 50, and if the color point P is outside the line segment |LmPi|, mapping the color point P to the target color gamut, and then generating a color point P'; and step 50, converting L*a*b* values of the color point P, after being mapped to the target color gamut, into RGB number values. The method of improving out-of-gamut color overlap mapping of the invention enables variouscolors to no longer be mapped to the same color point.