Abstract: Chinese torreya (Torreya grandis Fort. cv.'Merrillii') is an endemiceconomic tree species in our country, which is dioecious. The chromosomalanalyses of the cells in root tip, show that the female plant has a pair ofheteromorphic sex chromosomes, which are heterogametic sex and belong toZW type. The male plant is homogametic sex and belong to ZZ type. Thekaryotype of the female plant is 2n=2x=22=22m (2SAT+ZW), while thatof the male plant 2n=2x=22=22m(2SAT+ZZ) In the somatic cell of the female plant there is only one shortestz chromosome, and the difference of the sizes between the two chromocentres of interphase nuclei is notable. The male plant has a pair of shortest Z chromosomesand the sizes of the chromocentres of interphase nuclei are the same. According to these characters the sexuality of the plant can be discriminated atearly stage,

Key words: Chinese torreya, Karyotype, Sex-discrimination