The 40 samples and distribution information were obtained by field investigation, that distributed in 7 counties of Guizhou and Guangxi provinces, one of the main habitats of Cinnamomum migao in China. We investigated the chemotype and geographical locations of 40 samples of the Miao ethnic herb Fructus Cinnamomi (Cinnamomum migao) from 7 counties of Guizhou and Guangxi provinces, one of the main habitats of this medicinal herb in China. The nine major volatile oils including isopropyl ether, α-pinene, β-pinene, α-phellandrene, D-limonene, 1,8-eucalyptol, sabinene, α-terpineol and cyclohexane, were analyzed with gas chromatography-mass spectrometry (GC-MS) and correlated with geographical distributions of the samples in Geographic Information System (ArcGis). The following results are presented in this report: (1) Based on composition of the nine volatile oils, Fructus Cinnamomi can be classified into three chemotypes: HS type, PJ type and LS type, and the chemical composition of the latter two types are more similar. (2) There are apparent correlations between chemotypes and geographical locations of Fructus Cinnamomi. The HS type appears mainly in the southwest regions of the Miaoling Mountain and the Hongshui River basin, normally below 800 meters in altitude (relative to the sea level). This chemotype contains high amounts of 1,8-eucalyptol (>60%) and α-terpinol (>55%), and low amounts of α-phellandrene and D-limonene (both <10%). In contrast, the PJ type is distributed mainly in the southeast of the Wumeng Mountain, the Nanpanjiang River basin and the Beipanjiang River basin, often more than 800 meters above sea level. Compared to the HS type, the PJ type is characterized by lower amounts of 1,8-eucalyptol (<40%) and α-terpinol (<50%), and higher amounts of α-phellandrene and D-limonene (between 10% and 20%). The LS type is distributed mainly on the Cenwanglao Mountain, also in regions about 800 meters above sea level. This chemotype contains less than 40% of 1,8-eucalyptol. Based on these findings, we propose a hypothesis that climatic factors such as the intensity and the average length of sunshine affect significantly volatile oil compositions in Fructus Cinnamomi to a certain degree.