This paper studies the composition and geographic elements of flora in Daheishan National Nature Reserve of Liaoning Province,northeastern China by applying the methods of phytogeography,and based on field plant investigation and the relevant literatures.The results showed that among the wild vascular plant species,the the angiosperms is dominant,followed by ferns and gymnosperms which accounts for the smallest proportion.At the level of genus and species,the regional advantage is more obvious than the families and large families and genera,higher strength for differentiation is presented,followed by 6 to 20,the medium has a larger population and has certain advantages,again for the oligotypic families,single species effects on regional flora degree is weakest.The floristic composition is mainly in plant area of north temperate component and has some proportion of the flora of tropical nature.The region has 6 genera endemic to China,and reflectes the protection valure of the uniqure plant resources in the area.