Abstract: The chromosomes karyotype of Agropyron mongolicum Keng was analyzed in this paper and the process of its mitotic division was observed and recorded. The results showed that the karyotype formula of A.mongolicum Keng was 2n=2x=12m （2SAT） ＋ 2sm and the karyotype was 2A type.1 -2 B chromosome can be observed and their shapes were dot or short-stick in the metaphase of mitotic.