This study was to research the effects of feeding milk replacer and starter on growth performance, serum biochemical indexes and nutrient apparent digestibility of lambs during mid-late lactation. Seventy five 30-day-old lambs with similar weight were selected and randomly divided into 5 groups with 3 replicates per group and five lambs per replicate. Lambs were fed milk replacer 1+ starter (group A), milk replacer 1 (group B), milk replacer 2 (group C), breast milk + starter (group D) and breast milk (group E), respectively. At 30, 40, 50, 60, 70 days of age, body weight and body size were measured. A total of 3 consecutive days of fecal sampling was carried out to determine nutrient apparent digestibility at 68 to 70 day of age. Jugular venous blood was collected at 70 days of age to determine serum biochemical indexes. The results showed as follows:1) at 30, 40, 50, 60, 70 days of age, body weight, body length, body height and heart girth of group D were higher than those of groups A and E, group E was higher than group B, and there were no significant differences between groups B and C (P>0.05); but during 60 to 70 days of age, average daily gain of group A was significantly higher than that of group D (P<0.05), group B was significantly higher than group E (P<0.05). 2) Serum urea nitrogen content and the activities of alanine aminotransferase, glutamyl transferase, lactate dehydrogenase were not significant different among groups (P>0.05); serum total protein and triglyceride contents of group D were significantly higher than those of group A (P<0.05), triglyceride content of group E was significantly higher than that of groups B and C (P<0.05); there were no significant differences of serum albumin and globulin contents among groups A, D and E (P>0.05), but group D has higher values, group E was significantly higher than groups B and C (P<0.05); serum glucose content of groups A, D and E was significantly higher than that of groups B and C (P<0.05); serum alkaline phosphatase activities of group A was significantly higher than that of other groups (P<0.05); all the above serum biochemical indexes of groups B and C were not significantly different (P>0.05). 3) Feed intakes of various nutrients of group A were significantly higher than those of groups B and C (P<0.05), and the differences were not significant between groups B and C (P>0.05); the apparent digestibility of dry matter, calcium and phosphorus had no significant difference among groups (P>0.05); the apparent digestibility of gross energy, crude protein, neutral detergent fiber and acid detergent fiber of group A was significantly higher than that of groups B and C (P>0.05), groups B and C had no significant difference (P>0.05). It is concluded that feeding milk replacer and starter has different effects on performance, serum biochemical indexes and apparent digestibility of nutrients of lambs, the feeding mode of milk replacer and starter can realize early weaning of lambs, which has certain value of popularization.