This study estimated characteristics and genetic parameters for milking traits in Holstein dairy cattle. Daily records (12,561) were available from a hundred fifty four lactating cows with sixty six sires at National Livestock Research Institute from November, 2005 to April, 2006. The cows were fed same rations, and were milked twice daily using milking parlour equipped with Alpro-system?? to collect milking records automatically. The experimental cows have averaged 1.9 parities, 139.7 days in milk, and 13kg milk yield per milking. Average milk flow was 64% of peak milk flow. Milking duration, peak milk flow, average milk flow, and milk yield per milking were 5.57±1.67 minutes, 3.58±0.79kg/minute, 2.28±0.51kg/minute, and 13.02±4.09kg, respectively. All traits in the morning milking were higher than those of in the evening milking, and were also increased with parity. Heritabilities for milking duration, peak and average milk flow, and milk yield per time were 0.49, 0.70 0.58 and 0.36, respectively. The genetic correlations of milking duration with peak milk flow, average milk flow, and milk yield per time were 0.48, 0.54, and 0.41, respectively. The correlations of milk yield per milking with peak milk flow and average milk flow were 0.23 and 0.30, respectively. In conclusion, milk flow was increased with milk yield; however milk flow was opposite relationship with milk duration. Further studies are not only necessary to warranty genetic parameters, but pre-installation of automatic recording system to collect daily milking record is also necessary.