The essential oil from Cymbopogon citrus is known for its use in various fields such as perfume, cosmetic, pharmaceutical and food industries. In this study, the merits of Cymbopogon citrus essential oil extracted by both solar energy and hydro-distillation were evaluated, including the extraction yield and time, chemical composition (by gas-chromatography coupled with mass spectrometry, GC/MS), and antioxidant activity (DPPH free radical scavenging capacity). The energy consumption by these two methods was also investigated. The results show that the yields by solar energy extraction and hydro-distillation are nearly the same with 1.28% and 1.30%, respectively. The corresponding important compositions of citral (neral+geranial) are 66.53% and 60.78%, and DPPH free radical inhibitions in terms of IC50 are 33.52mg/mL and 38.42mg/mL. That is, the antioxidant activity of the oil extracted by solar energy is better than that by hydro-distillation. Moreover, hydro-distillation consumes 858 kWh of electricity per kg of essential oil whereas solar energy extraction is free of any utility electricity. Thus, a completely sustainable green extraction method by solar energy is a viable alternative to the traditional technique for extracting the Cymbopogon citrus essential oil.