Abstract: The physical chemical properties of monascorubin were investigated in order to discuss the application feasibility of monascorubrin in dyeing and printing industry. The solubility, acid and alkali resistance, hot stability and light stability of monascorubin were researched. The effect of mordants on monascorubin was also investigated. The results showed that monascorubin could be dissolved in water. It was relatively stable under 100 ℃. In the range of pH 3~11, it was stable for pH values. Monascorubin maintained stable in the ultraviolet radiation, but sensitive to the visible light. Ferrous sulphate had little effect on monascorubin, while potassium dichromate and copper sulphate had disadvantageous effect on the pigment. Praseodymium chloride had the protection of color, which would improve the color fastness of monascorubin.