Abstract: This study was carried out to evaluate the effect of supplementing different concentrations of N-acetyl-cysteine in the extender on cryo-preservation quality of chicken semen. The fresh semen samples from Anka breeder chickens were collected and diluted with two separate extenders （A and B） each adding different concentrations （0.013 0 and 0.002 6 mol/L） of N-acetyl- cysteine. The diluted semen samples were subsequently cryo-preserved and the preservation time, survival index and deformity rate were determined. The results revealed that in the A extender, there were no significant differences in preservation time and survival index between the 0.013 0 mol/L of N-aeetyl-cysteine treatment samples and 0.002 6 mol/L of N-acetyl-cysteine treatment samples （P〉0.05）, but preservation time and survival index of the two N-acetyl-cysteine treatment samples were significantly higher than those of control （P〈0.01）; in the B extender, the preservation time and survival index of the 0.013 0 mol/L of N-aeetyl-eysteine treatment samples were significantly higher than those of 0.002 6 mol/L of N-acetyl-cysteine treatment samples and control （P〈0.01）, but no significant differences in preservation time and survival index between the 0.002 6 mol/L of N-acetyl-cysteine treatment samples and control were observed （P〉0.05）. The addition and adding levels of N-acetyl-cysteine in the extenders had no obvious effect on the sperm deformity rate of Anka breeder chickens （P〉0.05）.