The diploid and autotetraploid common buckwheat, their autotriploid hybrids and trisomics were studied comparatively on aspects of the chromosome behavior at meiosis of pollen mother cells (PMCs) and the fertility of pollen grains. The results of observation of meiosis MI of PMCs showed that the average configurations of chromosome pairing in the autotetraploid variety Emka, its inbreeding line Emka-1 and autotriploid hybrids are 4x=0.67I+11.60+0.32+1.79IV=32, 4x =0.71I+7.42+1.19+ⅡⅢⅡⅢ3.22IV=32, and 3x=4.71I+4.71+3.29Ⅱ=24Ⅲ, respectively. The averages of micronuclei number in TⅡ cells in the diploid variety Siva, autotetraploid Emka and Emka-1, and the autotriploid hybrids are 0.03, 0.09, 0.20, and 0.86, respectively. Fertility of pollen grains showed that Siva has the highest fertility of pollen grains (the dyed rate of pollen grains in I2-KI solution is 98.89%), followed by autotetraploid Emka and Emka-1 (95.33% and 93.33%) and the autotriploid hybrids (only 31.28%) with the lowest fertility. The correlation analyses showed that there is significantly negative correlation between dyed rate of pollen grains (x1) and the average of univalent number (x2) or the averages of micronuclei number (x3), with r12=-0.996** or r13 =-0.993** respectively and significantly positive correlation (r23=0.994**) between x2 and x3, indicating that the number of univalent is one of the important factors resulting in formation of micronuclei at TⅡ of meiosis and that univalent number and micronuclei number can cause genetic and physiological imbalances and then result in an increase of abortion of pollen grains. In the autotriploid hybrids backcrossed with diploid variety Sobano there are 27.72% rate of empty seeds set and only 3.08% rate of normal seeds set. Among 34 normal achenes of the autotriploid hybrids, there were 6 double trisomics (2n+2), 23 trisomics (2n+1) and 5 diploid plants (2n). The segregation of short-style (Ss) and long-style (ss) plants in back-crossing progenies of Tr1-18 trisomics showed that the S gene locates on Tr15 trisomics of common buckwheat.