Abstract: Gardenia yellow pigment that was bought from the market was taken as experimental material in the paper. The influence of extracting pressure, temperature,time,CO₂ flow,modifier on the OD ratio of the gardenia yellow pigment was first studied systematically under supercritical condition. The results showed that the condition of high pressure,high temperature and adding modifier is suitable to decrease OD ratio and achieve the goal of purifying gardenia yellow pigment.