Objective To investigate the relationship between the homocysteine,sperm DNA fragmentation index and sperm counts of male with severe impaired spermatoqenesis.Methods From December 2015 to February 2017,56 male patients with severe impaired spermatoqenesis were enrolled in the study.The patients were divided into two groups according to the WHO criteria:severe oligozoospermia and azoospermia group (n =25) and oligoasthenoteratozoospermia group (n =31),and the control group was a male with no reproductive impairment (n=27).The sperm parameters were analyzed by using the computer automatic semen analyzer,sperm DNA fragmentation index and serum Hcy level were detected by sperm chromatin diffusion method and enzyme colorimetric method.Results The median of Sperm DNA fragmentation index and homocysteine level in control groups were 33％ [95％CI(29.0％ ～34.4％)] and 13.2 μmol/L [95％CI(12.4 μmol/L～14.2 μmol/L)],and in severe spermatogenesis groups in these two indicators were 21％ [95％CI(19.0％ ～24.0％)] and 8.9 mol/L [95％CI(8.4 μmol/L～ 9.4 μmol/L)],respectively.The results of these two items were higher than the control group,the difference was statistically significant (t=6.793～7.543,P=0.000).Sperm survival rate in normal control group and severe spermatogenesis group was 71％ [95％ CI(67.8％ ～75.1％)] and 57％[95％CI(52.3％ ～58.0％)],respectively,and the difference was statistically significant (t=-8.475,P=0.000).Sperm DNA fragmentation index was positively correlated with serum Hcy level and sperm concentration,Passing-Bablok regression analysis was:Y=10.705 +0.053X,Y=21.071+0.286X,and Hcy level was negatively correlated with sperm concentration.Conclusion The increase of Hcy level and sperm DNA fragmentation index may be an importantcause of male with severe impaired spermatoqenesis,but the specific mechanism remains to be further studied.