The study on the dimethylformamid (DMF) optimization for maintenance sperm quality of the carp fish (Cyprrnus carpio L.) post-thawing has been performed. Sperm were collected by stripping method and were dissolved in the extender solution (DMF : Kurokura solution = 1 : 3). DMF concentrations were 0%, 5%, 10%, and 15%, respectively. The soluble sperm were kept on the 0.2mL of straw and were cryopreserved by the slow freezing method.Sperm analysis were carried out at the time of collection, post-equilibration, and post-thawing, respectively. Some parameters of the sperm quality observed were spermatozoa motility, viability, and abnormality. All data were analyzed by Analysis of Varians (ANOVA). DMF 10% were significantly (cc = 0.01) kept spermatozoa motility, viability, and abnormality relatively higher than DMF 0%, 5%, and 15%. These results suggest that DMF 10% is the optimize condition for maintenance sperm quality post-thawing.