OBJECTIVE： To optimize the formulation of rare ginsenoside Compound K （CK） mixed micelle， and to investigate its in vitro release and apparent permeability coefficients （Papp）. METHODS： Using soy lecithin and vitamin E polyethylene glycol 1 000 succinate （TPGS） as excipients， CK mixed micelle was prepared by solvent evaporation method. Using drug-loading amount， encapsulation efficiency and particle size as index， orthogonal test was adopted to optimize feeding amount， the ratio of granulesten to TPGS and hydration volume； the micelle prepared by optimal formulation was investigated in respects of form， particle size， drug-loading amount， encapsulation efficiency， solubility， in vitro release； Papp of colon adenocarcinoma Caco-2 cell model was also inspected. RESULTS： The optimal formulation was as follows as feeding amount 1.0 mg， the ratio of granulesten to TPGS 1 ∶ 1， hydration volume 10 ml. The mixed micelles were spherical or spheroidal； the average particle size was （110±2.69） nm， and drug-loading amount was （4.32±0.19）％， entrapment efficiency was （92.23±2.76）％， and average solubility was （469.21±0.024） μg/ml； 150 h accumulative release rate was （66.19±0.027）％ （n＝3）. Papp of CK crude drug and CK mixed micelle were 26.20 and 3.78 （n＝6）. CONCLUSIONS： The optimized preparation technology is feasible， and CK mixed micelle is prepared successfully.