Toxicity effect of five plant essential oils : Jojoba, Neem, Garlic, Peppermint and Ginger were determined against Spodoptera littoralis. The results showed that Jojoba oil was the most potent followed by Neem , Garlic and Peppermint Ginger oil showed to have less toxic effect. The effect of LC50 of the tested oils on the in vivo inhibition of Na+,K+-ATPase from Spodoptera littoralis brain was assayed. The interaction of plant essential oils with Phenothrin on the in vivo inhibition of Na+,K+-ATPase was investigated. Results proved that pretreated of Jojoba oil with Phenothrin incressed the percentage inhibition which found that to be 96.7% and 92.6% for lab and field strain respectively, while the percentage inhibition found by pretreated the Neem oil with Phenothrin were 90.5% and 86.7% for lab and field strain Spodoptera respectively. In the other hand Garlic, Peppermint and Ginger showed very weak inhibitory effect (less than 50%) on the Na+,K+-ATPase activity. The results emphasized that I50 and Ki values decreased when Jojoba and Neem oil pretreated with Phenothrin, so there were significant differences among the chemical combinations, which caused more reduction effect than single treatment, and they affected enzyme activity by the same trend so results proved that Na+,K+-ATPase was sensitive to the Jojoba and Neem oil. Generally of essential oils pretreated with Phenothrin will produce a new trend so as reduce the field dose of the Pyrethroid insecticides, enhance the role of beneficial insects and reduce the cost of pest control.