The kinetics of leaching flavonoids from Pueraria Lobata with ethanol was investigated. The effects of leaching temperature, mechanical agitation rate, concentration of ethanol and feed particle size on leaching kinetics were examined. It is found that the smaller the feed particle size or the higher the leaching temperature, the higher the leaching rate. The leaching process can be described by the shrinking-core model. The apparent activation energy is 10.8kJ.mol(-1), suggesting that the leaching process is controlled by the inner diffusion. An empirical equation relating the flavonoids leaching rate constant to the feed particle size and leaching temperature was expected.