Objective: To optimize preparation technology of citronellol microemulsion gel and study on its in vitro antibacterial property. Method: The prescription of citronellol microemulsion was optimized by pseudo-ternary phase diagram with the percentage of microemulsion area as index.Single factor tests and orthogonal test were adopted to optimize formulation technology of citronellol microemulsion gel with appearance

viscosity

ductility

greasiness as indexes.Tube double dilution method was used to investigate minimum inhibitory concentration(MIC) and minimum bactericidal concentration(MBC) of citronellol microemulsion gel to the tested bacteria.The bactericidal efficiency of citronellol microemulsion gel and citronellol microemulsion were tested by the experiment of time-sterilization efficiency. Result: Optimum prescription of citronellol microemulsion gel was as follows:citronellol of 0.518%

Kolliphor HS 15 of 1.037%

ethanol of 0.667%

carbomer-980 of 0.8%

glycerol of 5%

water of 91.978%.The acquired microemulsion exhibited nattier blue

it was uniform and transparent with the average particle size of 54.9 nm and Zeta potential of -10.22 mV.The MIC and MBC of citronellol microemulsion gel were 1.667 g ·L-1 for the tested bacteria(Staphylococcus aureus and Candida albicans).Time-sterilization efficiency indicated sterilizing rates were 100% of citronellol microemulsion gel to the tested bacteria at 2 h. Conclusion: This optimized formulation technology of citronellol microemulsion gel is stable and feasible

this preparation has a rapid bactericidal effect on S. aureus and C. albicans.