Abstract: This is a study on the pollen abortion in five backcross generations of "Red-awned wild rice × Liao-tan-zao". Various abnormalities were observed in the whole period of microsporogenesis. Pollen development was usually arrested before the binucleate stage, resulting in abortion of pullen grains finally. Pollen abortion took place mainly at the late uni-nucleate stage. On the whole, various abnormalities in pollen abortion were found in all the five backcross generations.