The invention relates to Basma hexyl and a preparation method thereof, and belongs to the technical field of drugs and phytochemistry. The separation and obtaining of Basma hexyl comprise specific steps as follows: lower tobacco leaves of oriental tobacco Yunxiang basma No.1 are collected, dried in the shade and smashed, and the smashed leaves are screened by a 40-mesh sieve and taken as a raw material; the raw material is soaked in a methanol solution and extracted, reduced-pressure distillation and concentration are performed, and extract is obtained; the extract is subjected to extraction by ethyl acetate and subjected to silica gel column chromatography separation, thin layer chromatography silica gel plate separation and HPLC (high performance liquid chromatograph) purification finally, and the pure compound is obtained. Basma hexyl is obtained by separation from the oriental tobacco Yunxiang basma No.1 for the first time, and the compound is novel in structure, has multiple biological activities, and particularly has better anti-TMV (tobacco mosaic virus) activity, thereby providing important enlightenment for further research of oriental tobacco plant as an anti-TMV medicinal plant resource and being capable of applying to research, development and preparation of anti-TMV drugs.