Abstract: The microcapsules of peppermint essential oil were prepared by the composite coagulation method, which were made of natural polymer gelatin and arabian gum powder as wall materials, and peppermint essential oil as core material. The effects of different process conditions on the embedding rate and particle size of peppermint essential oil microcapsules were investigated by single-factor tests. The morphological structure and thermal stability of the microcapsules were also characterized by SEM, TEM, FT-IR and TG. The results showed that the oil content of microcapsules prepared was 44.9%, and the average particle size was 5.8 μm with the mass fraction of shell material 2%, ratio of core to shell 2∶1, the pH 3.7, the stirring speed 600 r/min and the curing time 6 h. The result of FT-IR confirmed that the essential oil of peppermint was successfully coated by wall materials. SEM and TEM analysis showed that the microcapsules were in the shape of regular round spheres, and the shell-wall materials were combined to form a "white-on-black" core-shell structure by electrostatic interaction, with a diameter of about 2 μm and a thickness of about 0.6 μm. The TG showed that the mass residue of peppermint essential oil was only 5.4% at 130 ℃. Comparatively, the mass loss of peppermint essential oil microcapsules could be found only at the temperature higher than 190 ℃, which showed that the thermal stability of peppermint essential oil was significantly improved after embedding. Thus, the quality loss and thermal stability of peppermint essential oil were improved by microencapsulation.