Abstract: In this paper, the chromosome numbers and karyotypes of Allum tuberosum were observed. The chromosome numbers of the most microspores are n= 16, a few are aneuploid. According to these facts, karyotype formula n= 2x = 16= 14m + 2st(SAT) was obtained. The fertility and tetrasporic micronucleus of microspore were observed too. They are 48% and 23.6% respectively. These results confirmed that the karyotype of Allium tuberosum is the isotetraplont which had been reported by others.