Abstract: Heterodichogamy, which is dispersed and reported in 20 genera from 13 families of flowering plants, is one of the evolutionary pathways from monoecy to dioecy. Heterodichogamous populations usually contain two sexual morphs, protogynous and protandrous, which are synchronous and reciprocal, and thus can reduce selfing rate. Generally, mating type is stable for an individual.Whereas,transitions among sexual phenotypes are reported in several species, though the rate is very low. There are separate completely between sexual functions(male-female flowering)within individual trees in many heterodichogamous plants, while partly overlaps have been found in several species. The inheritance pattern of mating system that a dominant-recessive Mendelian factor of one locus and two alleles determines mating type, and two genetic morphs co-occurs, typically at a ratio of 1:1 in a population has been confirmed in Juglans and Carya. However, little information at molecular level in other heterodichogamous species is available to support this hypothesis. Pattern of sex determination in heterodichogamous plants is trim variant. Sex differentiation of those plants is not only genetically controlled by genes of sex determination, but also is inductively regulated by phytohormones. However, hormonal function for sex differentiation is quite different among different species. Anatomical data from an individual plant revealed that developmental progress of female and male as well as ripening time is asynchronous. However, data from other sources is very few. Therefore, it is urgent that more evidences should be expoited to elucidate the mechanism of heterodichogamy.