This work was carried out to investigate the performance of growing period of large-type Korean native ducks. A total of four hundred twenty female and male duck chicks generated from A and B strains of ducks. Groups were four crossbreds (3 replications/crossbred, 35 birds/replication) as $2{ imes}2$ factors (2 strains, A and B; 2 genders, female and male). On the body weight, male of B strains was the highest among 4 treatments after the age of 4 week (P<0.05). Body weight of B strain was higher than that of A strain at all period (P<0.05). Body weight of male was higher compared to that of female after the age of 4 week (P<0.05). On the body weight gain, male of B strain was the highest and female of A strain was the lowest among 4 treatments at 0~8, 0~12, 0~16 and 0~20 weeks (P<0.05). Body weight gain of male was higher than that of female after the age of 4 week (P<0.05). On the feed intake, male of B strain was the highest among 4 treatments from the age of 0 week and to the age of 4, 12, 16 and 20 week (P<0.05). Feed intake of male was higher than that of female at 0~12, 0~16 and 0~20 weeks (P<0.05). On the feed conversion ratio, male of B strain was the highest among other treatments 0~4 weeks and female of A strain was at 0~8 and 0~12 weeks (P<0.05). Feed intake of female was higher compared to that of female at 0~8 weeks and male was high at 0~20 weeks. These results provided the basic data on the record of growing phase of large-type Korean native ducks.