In this study,we examined the chromosomes numbers and karyotypes of 11 populations of Allium wallichii Kunth from the northwest and central region of Yunnan.(1)Triploid individuals were found in two tetraploid populations which grew near diploid populations.The karyotypes were 2n=3x=21=[6m(2sat)+8sm]+(3m+4sm) and 2n=3x=21=[4m(2sat)+10sm]+(2m+4sm+lst),respectively.(2)Hexaploid seeds were found in tetraploid population for the first time.The karyotype were 2n=6x=42=15m(3sat)+27sm.(3)Considering the karyotypes and cytogeographic information,it can be inferred that the triploid was formed via hybrid between diploid and tetraploid,while fusion of an unreduced tetraploid gamete（n=4x=28） with a reduced diploid gamete（n=2x=14） formed hexaploid.Our results supported that A.wallichii Kunth originated in the high elevation region of northwest Yunnan.In addition,combining both previous studies and our present results,we discussed the possible mechanisms of polyploidy formation in A.wallichii Kunth.