The invention belongs to the field of natural plant extracts and application, in particular to a pepperweed seed extract and application thereof in tobacco. The extract is prepared by the following steps: drying and grinding pepperweed seed after impurity removal; and extracting with water or ethanol or aqueous solution of ethanol, petroleum ether, ethyl acetate, normal hexane and acetone for 5 minutes to 10 hours; and filtering extracting solution, and concentrating under reduced pressure to obtain the pepperweed seed extract. The components of the pepperweed seed extract with pharmaceutical effect are maintained completely and extracted fully, the method is simple and the pertinence is strong; when added into the tobacco, on the premise of not changing the conventional processing technology and the original performance of the tobacco, the pepperweed seed extract can improve the safety and comfortableness in the smoking process, and functional components beneficial to a human body are increased; and simultaneously, Chinese style cigarettes with certain characteristics are formed.