This study was conducted to estimate genetic parameters of milking speed. For this purpose, information of 5292 milking time of 1762 dairy Holstien cows from 7 industrial herds of dairy cow in Isfahan province from October 2015 to March 2016, were used. To evaluate milking speed, the average of milking speed was used as criteria. For this purpose, individual total milking time was recorded by digital stopwatch and then the average of milking speed was calculated in kg per minutes by dividing milk yield on total milking time. Moreover, to evaluate the relationship among traits related to udder type and milking speed, the udder type traits were recorded in one of the investigated herds. In addition to milking speed, to define the best criteria for evaluation of milkability, the traits maximum milking speed and 2-min milk yield were recorded in three herds of investigated herds. Moreover to evaluate the correlation among milking speed with milk components, the traits milk protein percentage, milk fat percentage and somatic cell score (SCS) were recoreded at the same day that milking speed were recorded. Least square means of milking speed was estimated 2.11(±0.01) kg per minutes. The Results indicated that effect of recording month-herd, lactation, lactation stage on milking speed were significant (p 0.01). The estimated heritability of milking speed was 0.22(±0.07). Moreover, high genetic correlation were estimated between milking speed with milk yield (0.90) and total milking time (0.83). The genetic correlation between milk fat percentage, milk protein percentage and SCS with milking speed were -0.69,-0.47 and -0.36 respectively which indicate that with higher milk concentration or higher bacterial load, the milking speed were decrease. Among udder type traits, the rear udder height had highest correlation with milking speed (-0.73). In compare milkability criterias, the trait 2-min milk yield was better than other traits, because it is much easier to measure and have higher heritability (0.36±0.14). Also the genetic correlation of this trait with other traits were high. In general, the result of this study indicated that considerable gains in milking parlor throughput may be achievable with selection for faster milking speed. Keywords: milking speed, total milking time, udder type traits, dairy cows , 2-min milk yield, genetic parameters