Abstract: Through the comparative studies of alkaloids, steroids, triterpenoids, cyanogenic glucosides and fatty acids in the relevant orders of Monocotyledonae and “Nymphaeales”,and Ranunculaceae, the authors point out the close phylogenetic relationship between the Ranunculaceae and Liliales. They support the hypothesis that Liliales, the oldest primitive Monocotyledonae, was originated from Ranunculaceae, and they disagree with the view point of Takhtajan who advocated that Alismales evolved from Cabom-baceae.