Abstract: The Objective of this study was to evaluate the effects of alfalfa saponins on growth performance and blood biochemical index of weaned piglets. The Piglets were weaned at 9.2 kg and divided into 4 treatments with three replicates each treatment, and four Piglets per replicate according to birth date, litter, and gender, using complete random single factorial design. The levels of alfalfa saponins were 0%, 0.25%, 0.5%, and 1.0%, respectively. The Results showed that: 1) The daily gain of piglets fed with 0.25% and 0.50% alfalfa saponins were significantly higher than that of control group, and their relative growth rate were increased, and the feed weight ratio of the trial groups were lower compared control group. 2) Alfalfa saponins had positive influence on the digestibility coefficient of crude fat, crude ash and neutral detergent fiber for feed; however, the digestibility coefficient of crude protein in feed was reduced. 3) The number of red blood cell and white blood cell of blood was improved when the piglets was fed with alfalfa saponins, for example, those of 0.50% group were very significantly higher than that of control group(P<0.01). 4) The Urea nitrogen content of the trial groups was significantly lower than that of control group. With the alfalfa saponins level increased, the aspartate aminotransferase activity was increased, but the serum glucose was opposite (P>0.05), alkaline phosphatase content of the trial groups were very significantly higher than that of control group(P<0.01). The result of the study suggested that the suitable alfalfa saponins can improve the production of weaned piglets, and the appropriate amounts of alfalfa saponins in weaned piglets diet was between 0.25%-0.50%.