Abstract: Forest landscape color is an important factor influencing the aesthetics of forests. In order to understand the influence of forest landscape on college students’ mental health, this paper comprehensively studied the influence of four forest landscape colors, red, yellow, green, and mixed colors, on college students’ mental health through a comparative experiment method with the help of monopolar EEG technique and a questionnaire survey. It was found that green had the greatest enhancement on human relaxation. It was followed by mixed colors, yellow and red in that order. Green was the most calming and hardly brought negative emotions, and also reduced fatigue, tension, and irritability; red made subjects feel calm but makes some of them nervous; yellow made most subjects relax, and was the most exciting and rarely triggered negative emotions; the richness of forest landscape colors was positively correlated with its effect on positive emotions and the effect of mixed colors on people’s psychology. The impact of mixed colors on human psychology was greater than that of monotone colors. Mixed colors showed more appreciation and practical value, and their emotional indicators were generally stronger than other colors in the categories of “relaxing” and “exciting”.