This experiment was carried out to study milk producing capacity and milk composition of crossbred Korean native Cow with Holstein sire. Some of the findings are as follows: 1. Crossbred F₁ female(Korean native ♀×Holstein ♂) has produced 9,215㎏ of milk during 4 lactation periods mating average production per one lactation period, 2,303.8㎏. This was found to be much higher than the purebred native females production performance of 404.3㎏. 2. Peak daily production of crossbred was 18.5㎏ and peak monthly production was 473.7㎏. 3. Average lactation period of crossbred female was 280.8 days and was much longer than Korean native`s 170 days and the livestock experiment station`s old record of 236.4 days made in 1917. 4. The milk composition of crosobred F₁ was as follows: butterfat 4.79% protein 3.49% lactose 5.25% ash 0.70% water 85.79% S.N.F. 9.42%