Abstract: G banding karyotype analysis of peripheral lymphocytes in 217 patients with azoospermia or severe oligospermia were performed and the polymerase chain reactions(PCR) for AZFc of Y-chromosome in the blood from 7 cases with Y chromosome abnormality. The result is: out of 187 cases of azoospermia, 77(41.18%)patients with abnormal chromosome(number and structural aberration)； heteromorphic chromosome(Y chromosome polymorphisms and pericentric inversion of 9) and 46,XX sex reversal. Out of 30 cases of severe oligospermia, 4 patients with abnormal chromosome(structural aberration and 46,XX sex reversal). It is revealed that the aberration of sex chromosome causes the most serious spermatogenesis failure and some breakpoints of autosome may also affect spermatogenesis. The deletion of AZFc is also affect spermatogenesis.