This study was designed to evaluate the effects of dietary yeast polysaccharide levels on nonspecific immune response of Chinese Striped-neck Turtle(Mauremys sinensis). The experimental subjects (weight=134.7 ± 19.1 g) were randomly divided into four groups and were fed as follows for 30 days: a commercial diet as control (Ⅰ) and the same diet supplemented with 800 mg/kg (Ⅱ), 1200 mg/kg(Ⅲ), 1600 mg/kg (Ⅳ) yeast polysaccharide. After 15 and 30 days, the immune organ index, number of leucocytes, serum lysozyme and complement C₃、C₄ activity were detected. The results showed that compared to the control, there was no significant differences in experimental groups for the immune organ index (P >0.05), while the number of leucocytes and lysozyme activity were significantly increased (P <0.05), and the values were highest in group Ⅲ; After 15 days, the serum C₃、C₄activity in