Abstract: The aim of the present study was to investigate the effect of different restricted feeding and compensatory feeding programs on colon histological structure of ram lambs of Mongolian Sheep. A total of 30 4-month-old healthy ram lambs of Mongolian Sheep with moderate body condition and average weight of （20.70±3.51 ） kg were included and randomly and averagely divided to control group （CG） and feeding restriction group （RG）. The ram lambs received a compensatory feeding program for 60 days after they were restrictively fed for 60 days. All of the animals were reared in the same environment. At the end of the restricted feeding period, 5 ram lambs were selected from CG and RG and were slaughtered and sampled. During the compensatory feeding period, the remaining ram iambs from CG and RG were assigned to Leymus chinensis feeding group （CH and RH groups） and straw feeding group （CM and RM groups）. The CH and RH groups were fed green hay with concentrate to forage ratio of 5：5, and the CM and RM groups were fed straw with concentrate to forage ratio of 7：3. At the end of compensatory feeding period, all of the ram lambs were slaughtered. The colon tissue samples with a length of 3 cm were collected and were fixed in formaldehyde solution phosphate buffered （40 g/L, pH value=7.4）. The paraffin sections of the colon tissue samples were prepared and were stained routinely with hematoxylin and eosin. The thickness of mucosa layer, submucosa layer, internal circular muscle layer and outer longitudinal muscle layers of colon were measured by using microscopy. Due to the fact that the serous layer was prone to displace, exfoliate and injury, which produced errors in experiment, the thickness measurement of serous layer were not included in this study. The data were statistically analyzed by SPSS 21.0 software. The results showed that significant differences in thickness of colon mucosa layer between RG and CG were observed （P〈0.05）, no significant differences in thickness of submucosa layer, internal circular muscle layer and outer longitudinal muscle layers of colon between CG and RG were found （P〉0.05）. There were no significant differences in thickness of all layers of colon between RH and CH （P〉0.05）. Significant differences in thickness of colon submucosa layer between RM and CM were observed （P〈0.05）, no significant differences in thickness of mucosa layer, internal circular muscle layer and outer longitudinal muscle layers of colon between RM and CM were found （P〉0.05）. The combined data shows that the thickness of colon mucosa layer of ram lambs of Mongolian Sheep is increased after a period of nutrient restriction.