Objective：To analyze the features of chromosomal abnormalities and azoospermia factor（AZF） of males with severely im－paired spermatogenesis. Methods：G-banding and multi-PCR method were used to analyze the karyotypes of chromosome and AZF microdeletions respectively. Results：In 443 cases of azoospermia and 183 cases of severe oligozoospermia，79 cases（12.62%） of chro－mosomal abnormalities were found；68 cases（15.35%） in azoospermia group and 11 cases（6.01%） in severe oligozoospermia group. Meanwhile，the translocation karyotype 46，XY，t（4；8）（q35；q22） in severe oligozoospermia group was firstly reported. There were 68 cases（10.86%） of Y chromosome AZF microdeletions，accounting for 11.51% and 9.29% in azoospermia group and severe oligo－zoospermia group respectively. The deletion type AZFc was the most common，followed by AZFb and AZFd；the constituent ratio of the three types were 41.18%，20.59%，10.29%，respectively. In 68 cases of Y chromosome microdeletions，14 cases complicated with chro－mosomal abnormalities（10 cased in azoospermia group and 4 cases in severe oligozoospermia group）. Conclusion： Genetic abnormality is important for patients with severely impaired spermatogenesis. Detection chromosome abnormality and Y chromosome microdeletions is necessary before applying assisted reproductive technology in order to decrease the risk of abnormal gene inherited from the father.