Abstract: This paper summarizes the expression, origin, evolution, function and regulation of flower color in higher plants. The main expressions of flower with single color, changeable and motley, are resulted from a long period of evolution, its main function being to lure pollinators and protect the flower organs, especially petals. Flower pigments mainly consists of flavonoids, carotenoids and alkaloids. The chemical mechanism for the expression of flower color is the ratio of different type of pigments in petals; the anatomic and optical mechanism for the expression of flower color are the dimensional distribution of the pigments in petals and their effects on light; and the physiological mechanism are the pH of cell sap of petal, the developmental stage and the endogenous hormones of flower. External factors such as pollinators, fungal infection, mechanical damage, horticultural measures, light, temperature, water, mineral ions, and saccharides influence flower color. The variegation of petals originates chiefly from gene mutation and viral infection.