A total of 24 APRI line rabbit bucks having 2.65±0.11 kg live body weight at 20 weeks of age were used in this study. Bucks were divided into four similar groups, 6 bucks in each. Bucks in the 1st group were fed basal diet without any supplements as a control. While those in the 2nd, 3rd and 4th groups were fed the same diet supplemented with 50 mg nano-Cu (nano-Cu), 200 mg Cu sulfate (metal-Cu) or 200 mg Cu-Methionine (organic-Cu) per kg diet, respectively. Semen was collected biweekly at 28 – 36 wks of age for evaluation. APRI does were naturally mated by treatment bucks (24 does/group) at the last week of the experimental period. Results showed that bucks fed diet with nano-Cu had numerically higher (P<0.01) values for live body weigh and body weight gain, followed by those fed diet containing Cu as organic and metal form than a control group. The ALP activity and serum testosterone hormone concentration increased (P<0.05), being the highest values in the 2nd group. Supplemented rabbit bucks with nano-Cu in their diets showed the best (P<0.05) sperm characteristics including progressive motility, livability, and abnormality percentages of spermatozoa and sperm concentration. Sperm membrane integrity, fructose test, LDH activity and peroxidase activity in seminal plasma were better in nano-Cu group as compared to other treatment groups. The examination of buck semen by scanning electron microscope revealed lower types and proportion of sperm abnormality in the 2nd group compared to the other groups. The highest fertility rate (91.7%) was produced in nano-Cu dietary bucks' group, but did not differ significantly from that in metal-Cu (83.3%) and organic-Cu (87.5%) compared to 70.8% in control group. It can conclude that supplementation of the copper in Nano-particles form at a level of 50 mg/kg in the diet of rabbit bucks is recommended for improving semen quality and fertility for artificial insemination and natural breeding in rabbit production field.