The karyotpes were analysed via squash method in Prunus triloba and 4 related species which are P.persica L.,P.mume Sieb.,P.cerasifera ‘Pissardii’and P.armeniaca L..The results showed that the chromosome numbers of cultivar P.triloba ‘Ziyan’ was 42,while other P.triloba materials’ numbers were 64(2n=8x=64).All related species were diploid(2n=2x=16).Asymmetry index ranged from 57.68% to 63.08%.The relative length component of P.triloba ‘Ziyan’ was 2n=6L+9M₂+24M₁+3S.Among related species,P.triloba had the closet relationship with P.persica.