Application of essential oils in controlling plant pathogens is generally associated with difficulty due to low solubility in water, strong odor, physical and chemical instability. One of the ways to minimise these effects is to use a nanoemulsion system. It also increases the antimicrobial properties. In this research, after preparation of cinnamon (Cinnamon zeylanicum L.) essential oil (CEO), nanoemulsion of the essential oil was prepared and its physical and chemical properties were determined. The particle size of nanoemulsion was determined to be 115.33 +/- 3.97 nm. Emulsification and nanoemulsion of the essential oil along with thiabendazole as an antifungal agent at various concentrations of active ingredient were studied for control of Rhizopus stolonifera and Botrytis cinerea fungi, strawberry fruit decay. Results in solid Potato Dextrose Agar (PDA) medium indicated that emulsion and nanoemulsion of CEO have a significant difference in antifungal activity against B. cinerea and R. stolonifera. The minimum inhibitory concentration was 500 and 1,000 mu l fungi per liter of culture medium. According to the results of the research, essential oil nanoemulsion had a significant effect on the reduction of a fungal cartilage of strawberry fruit. In general, nano-emulsions of the essential oil showed more antifungal activity than essential oil. There was no significant difference in decay control between thiabendazole and CEO. The nano-emulsion of cinnamon oil at a concentration of 0.2% proved significant effect in reducing fruit decay and showed the lowest fruit infection (5.43%). Consequently, nano-emulsion of essential oil is recommended for the production of natural fungicides.