A rapeseed mutant resistant to imidazolidone was found as a volunteer in the soybean field treated by spraying imidazolidoneherbicide. The resistance of this mutant was steadily inherited and effective,which had been testified by consecutive assessment of several generations in 3 years. The mutant showed resistant to a dose of imidazolidone which was two times of the effective concentration of this herbicide. It is of great theoretical and practical significance for the identification of new herbicideresistant oilseed rape genes with independent intellectual property,also for the development of new varieties against environmental release restrictions.