This experiment was conducted to investigate effects of serotonin (5-HT) on performance and plasma and milk calcium transport related biochemical index of perinatal ewes. Thirty Bamei ewes with similar body weight were randomly allotted 3 groups, which were control group, 5-hydroxy-tryptophan (5-HTP) group (perfused 5-HTP) and tryptophan (Trp) group (perfused Trp), respectively, each group contained 10 ewes. Ewes jugular vein perfusion was conducted from prenatal day 7 to postpartum day 0, the perfusion dose of 5-HTP and Trp was 0.178 mg/kg BW, and the concentration was 0.1 mg/mL; the control group was perfused with the same dose of saline. The experiment lasted form prenatal day 7 to postpartum day 30. The results showed as follows:1) there was no significant difference in body weight of ewes among all groups (P>0.05). On postpartum day 5, 9 and 15, the milk yield of ewes in Trp group was lower than that in the control group (P>0.05); on postpartum day 9 and 15, the milk yield of ewes in 5-HTP group was higher than that in the control group (P>0.05). On postpartum day 16 to 30, the average daily gain of lambs in 5-HTP group was significantly higher than that in the control group (P<0.05). 2) On postpartum day 15, the plasma and milk calcium concentration in Trp group was significantly higher than that in the control group (P<0.05); on postpartum day 3, 6 and 15, the plasma and milk calcium concentration in 5-HTP group was significantly higher than that in the control group (P<0.05). On postpartum day 6, the plasma 5-HT concentration in Trp group was significantly higher than that in the control group (P<0.05); on postpartum day 30, the milk 5-HT concentration in Trp group was significantly higher than that in the control group (P<0.05); on postpartum day 6, 9 and 30, the plasma and milk 5-HT concentration in 5-HTP group was significantly higher than that in the control group (P<0.05). On postpartum day 3, 6 and 15, the plasma parathyroid hormone-related protein (PTHrP) concentration in Trp group and 5-HTP group was significantly higher than that in the control group (P<0.05). In conclusion, perfuse 5-HTP can promote the lactation of ewes, improve the average daily gain of lambs; perfuse 5-HTP and Trp can increase the concentration of calcium and 5-HT in plasma and milk and PTHrP in plasma.