The objective of this study was to explore the effects of dietary restriction level and realimentation on growth performance, digestion, metabolism and cellulase activity in ruminal fluid of small tail Han sheep. Forty 3-month old small tail Han sheep with average body weight (BW) of (19.77±1.34) kg were randomly split into four groups with ten sheep in each group by a single factor four levels design. The study lasted for 90 days. Control group (group Ⅰ) was fed ad libitum during the whole period; during 30-day dietary restriction period, three experimental groups were fed diets with different metabolizable energy (ME) and crude protein (CP) levels, which were designed to meet requirements of 500 (group Ⅱ), 400 (group Ⅲ) and 300 g/d (group Ⅳ) of daily gain recommend by NRC(2007), after that, a 60-day realimentation period (ad libitum) was started. Digestion and metabolism tests were carried out on 24 to 30 days and 84 to 90 days, respectively. The results showed as follows: 1) at dietary restriction period, dietary restriction level had significant effects on final BW and average daily gain (ADG) (P < 0.05), with the increase of dietary restriction level, final BW and ADG tended to be decreased, while feed to meat ratio tended to be increased. At realimentation period, final BW was not significantly different among groups (P >0.05); the compensation percentage in BW of groups Ⅱ, Ⅲ and Ⅳ was 104.36%, 101.71% and 99.61% of BW of group Ⅰ; dietary restriction level had significant effect on ADG (P<0.05); with the increase of dietary restriction level, ADG tended to be increased, while feed to meat ratio tended to be decreased. 2) At dietary restriction period, dietary restriction level had significant effects on the apparent digestibility of dry matter (DM), neutral detergent fiber (NDF) and acid detergent fiber (ADF) (P<0.05), and all were decreased with the increase of dietary restriction level, but no significant differences were found for organic matter (OM) and CP apparent digestibility (P >0.05). At realimentation period, the apparent digestibility of all nutrients showed no significant difference among the four groups (P>0.05). 3) At dietary restriction period, dietary restriction level had significant effects on nitrogen intake, nitrogen retention, nitrogen retention percentage (P<0.05), and all were decreased with the increase of dietary restriction level; urinary nitrogen/nitrogen intake tended to be increased with the increase of dietary restriction level, but was not differ significantly (P>0.05). No significant differences of fecal and urinary nitrogen among the four groups were found (P>0.05). At realimentation period, there were no significant differences of the nitrogen metabolism indices among the four groups (P>0.05). 4) On 1 to 30 days, cellulase activity in ruminal fluid of experimental groups tended to be decreased, while on 31 to 90 days, tended to be increased, and on 90 days, all experimental groups were higher than group Ⅰ. The present results indicate that short-term moderate dietary restriction with a realimentation period is not harmful for the growth performance, digestion and metabolism of small tail Han sheep.