A process for preparing Plectranthus amboinicus extracts comprising the steps of: a) contacting the dried Plectranthus amboinicus leaves with a leaf extracting solvent selected from water or alcohols to obtain a Plectranthus amboinicus crude extract; b) concentrating the Plectranthus amboinicus crude extract; and c) treating the concentrated Plectranthus amboinicus crude extract using a stirring separation method to obtain a Plectranthus amboinicus extract, wherein the stirring separation method comprises the steps of: a) diluting the concentrated leaf extract with a high-polarity solvent including water, methanol, ethanol or a mixture thereof, mixing the diluted leaf extract with an absorbing resin, and stirring the absorbing resin and diluted leaf extract; b) removing the liquid portion, extracting the resin with distilled water, and collecting the first extract; c) extracting the resin with a sub-high-polarity solvent having a polarity lower than that of said high-polarity solvent and collecting the second extract; d) extracting the resin with a medium-polarity solvent having a polarity lower than that of said sub-high-polarity solvent and collecting the third extract; and e) extracting the resin with a low-polarity solvent having the lowest polarity of the solvents used in the preparation process and collecting the fourth extract. a) contacting the dried Plectranthus amboinicus leaves with a leaf extracting solvent selected from water or alcohols to obtain a Plectranthus amboinicus crude extract; b) concentrating the Plectranthus amboinicus crude extract; and c) treating the concentrated Plectranthus amboinicus crude extract using a stirring separation method to obtain a Plectranthus amboinicus extract, wherein the stirring separation method comprises the steps of: a) diluting the concentrated leaf extract with a high-polarity solvent including water, methanol, ethanol or a mixture thereof, mixing the diluted leaf extract with an absorbing resin, and stirring the absorbing resin and diluted leaf extract; b) removing the liquid portion, extracting the resin with distilled water, and collecting the first extract; c) extracting the resin with a sub-high-polarity solvent having a polarity lower than that of said high-polarity solvent and collecting the second extract; d) extracting the resin with a medium-polarity solvent having a polarity lower than that of said sub-high-polarity solvent and collecting the third extract; and e) extracting the resin with a low-polarity solvent having the lowest polarity of the solvents used in the preparation process and collecting the fourth extract. a) diluting the concentrated leaf extract with a high-polarity solvent including water, methanol, ethanol or a mixture thereof, mixing the diluted leaf extract with an absorbing resin, and stirring the absorbing resin and diluted leaf extract; b) removing the liquid portion, extracting the resin with distilled water, and collecting the first extract; c) extracting the resin with a sub-high-polarity solvent having a polarity lower than that of said high-polarity solvent and collecting the second extract; d) extracting the resin with a medium-polarity solvent having a polarity lower than that of said sub-high-polarity solvent and collecting the third extract; and e) extracting the resin with a low-polarity solvent having the lowest polarity of the solvents used in the preparation process and collecting the fourth extract.