Objective: To evaluate the drug release in colon targeting of pH-triggered double layer colon target pellets of Sophora flavescens in vivo and in vitro. Method: Evaluate the drug release of the pellets in vitro with paddle method. Multi-slice spiral CT scanning was applied to detect the conveying of pellets in the digestive canal of human body in real time. Result: The pellets altogether released 26.18% of the drug in artificial gastric juice for two hours and in artificial intestinal juice for four hours

and accumulate to release 99.52% of the drug in artificial colon juice for two hours. The pellets were all emptied from stomach one hour after taking orally and all reached to colon after five hours. The disintegration of the pellets was not detected in stomach and small intestine

which started to disintegration after entering colon

disaggregated obviously after ten hours and completely disaggregated in colon after twenty-four hours. Conclusion: The pellets possess well drug release of colon targeting in vivo and in vitro.