Abstract: This experiment was conducted to assess the effects of dietary supplementation of yeast selenium on production performance and diarrhea incidence of weaned piglets. A total of 120 ＂Duroc ×Landrace ×Large White＂ weaned piglets were randomly divided into four groups with five repeats for each group and six piglets for each repeat. The basil diet of control group was supplemented with 0.3 mg/kg of sodium selenite,and that of the experimental groups 1,2,3 was supplemented with 0.1,0.3,0.5 mg/kg of yeast selenium. The experimental period lasted for 28 days. At the end of the experiment,the ending weight,daily gain,daily feed intake,feed/gain ratio,diarrhea incidence,and death and culling rate of the piglets from different groups were determined and statistically compared. The results showed that experimental groups 2 and 3 had higher ending weight,daily gain,daily feed intake and lower feed/gain ratio compared to control group（P〉0.05）; the diarrhea incidence of experimental groups 2and 3 was lower than that of control group（P〉0.05）,and the death and culling rate of experimental groups 2 and 3 was significantly lower than that of control group（P〈0.05）; no significant differences were observed in all of the tested indicators between experimental groups 2 and 3（P〉0.05）. In conclusion,as an organic selenium source,yeast selenium can improve the production performance and reduce the diarrhea incidence as well as death and culling rate of weaned piglets. Taking the feeding effect and production cost into consideration,the recommended addition of yeast selenium in feed was 0.3 mg/kg.