Objective To determine biological characteristics of Beagle during lactation period. Method Body weight, body length, tail length, body height, belly and chest were measured in Beagle of male and female, each 30, from birth to 62 days. Results With statistic analysis and drawing,the growth in first 30 days was almost the same, afterwards growth rate of male was higher than female. Growth indices of female and male suggested their simultaneous development.