Abstract: Sixty hybrid lambs of Mongolia sheep and Dorper sheep （Dumont hybrid lambs） which had similar birth weight and birth date and normal growth and development were chosen, and effect of early weaning of Dumont hybrid lambs on growth and development was studied. The results showed that from birth to 4-age period, the weight absolute growth and body size （body height, body length, chest girth and cannon circumference）of Dumont hybrid lambs increased quickly, so the period was peak of growth for Dumont hybrid lambs. According to the growth and development rule of Dumont hybrid lambs, it has important significance in development of local animal husbandry to strengthen the nutritional requirements and feeding management of lamb growth peak.