The compositions of the volatile oil of Arisaema decipiens Schott from two habitats were extracted by simultaneous distillation extraction (SDE) method, analyzed by gas chromatography–mass spectometry (GC–MS) and In vitro cytotoxic activities of both essential oils were explored by MTT test. 12 and 11 kinds of volatile components were identified from Guangxi and Sichuan respectively and the relative contents calculated by GC peak areas were 90.96% and 94.68%. 5 kinds of common components were (Z,Z)-9,12-Octadecadienoic acid, n-Hexadecanoic acid, Pentadecanoic acid, 5-Octadecyne and Z-11- Hexadecenoic acid. The main components of two volatile oils from Arisaema decipiens Schott were fatty acids, but they were different in the composition and relative amounts. Both essential oils inhibited cellular proliferation significantly against A549, Hela, HepG2 and HCT-116 cell lines with IC50 ranged from 43.66 μg/mL to 105.04 μg/mL.