[Objective] To investigate the effects of a compound plant-derived additive（formulated with rosmarinic acid, carvacrol,and tea polyphenols at a ratio of 1:3:1）on growth performance,serum biochemical indicators,and rumen microbiota of weaned lambs,and to provide a theoretical basis for its application in dairy goat farming. [Method] A total of 120 healthy 50-day-old weaned Saanen dairy goats were randomly divided into a control group and a treatment group,each with 60 lambs（10 replicates, 6 lambs per replicate）. The control group was fed a basal diet,while the treatment group received the basal diet supplemented with 5.0 g/kg of the compound plant-derived additive. The trial lasted 90 days. Growth performance,serum biochemical parameters,and the relative abundance of rumen microbiota were measured. [Result] Compared with the control group,the treatment group showed significant increases in final body weight（16.90%）and average daily gain（38.89%）（P<0.05）,and a significant decrease in feed-to-gain ratio（26.48%）（P<0.05）. Serum levels of triglyceride（TG）,globulin （GLB）,and total protein（TP）were significantly increased by 95.83%,27.72%,and 16.09%,respectively （P<0.05）. The relative abundances of Lachnospiraceae,Oscillospira, and other rumen bacteria were significantly reduced（P<0.05）,while that of Succinivibrio was significantly increased by 132.87%（P<0.05）. [Conclusion] The addition of the compound plant-derived additive to the basal diet of weaned lambs can significantly improve growth performance,serum biochemical indices,and rumen microbiota composition,indicating good potential for application in dairy goat production.