The objective of this study was to analyze the reproductive ability by strains and age in weeks of Korean native chicken and to compare the egg weight by body weight of Korean native chicken cock. Six strains (L=black, W=white, O=Ogol chicken, G=gray, R=red, and Y=brown) of Korea native chicken were used in this study. The fertility of strains W and Y were 89.6% and 86.3% respectively, and significantly higher than the other strains (p<0.05). Strains R and W showed high hatchability (90.7%, 89.6%, respectively) and strains L and O showed low rate (78.9%, 87.3%, respectively). There was no significant difference by weeks in each strain. The fertility was the highest at 28 weeks of age and the hatchability showed the highest value at 26 weeks of age. Egg weights of strains L and R were significantly high (p<0.05) but strains W and G were significantly low (p<0.05). Egg weight was higher in 1.65 ㎏ of Korea native chicken cock than in 2.00 ㎏ of Korea native chicken cock. These results suggest that the using average weight (1.65 ㎏) of Korea native chicken cocks could have an advantage for the feed cost savings and productivity improvement.