Chinese sturgeon, Acipenser sinensis, is in extremely Critically Endangered status. The Beijing aquarium is used as the major education and ex situ base for support this conservation, where the sturgeon can be cared individually. The blood cell is an important indicator of clinical for healthy judgment. In this study, the peripheral blood cells of 40 sturgeons distributed in 7 age groups were studied, including the > 30a (from the wild samples), 18a, 16a, 15a, 11a, 7a and 4a. The changes of blood indexes at different ages, development stages and stages of disease were analyzed, in order to apply in the health evaluation. ANOVA was used to analyze the variance between different age groups. Paired-Samples T Test was conducted to analyze the difference before and after gonadal development and the difference before and after disease. The average concentration of erythrocytes (RBC), leukocytes (WBC) and thrombocytes were 5.56 ± 1.19 × 1011/L, 16.53 ± 4.94 × 109/L and 15.53 ± 15.82 × 109/L respectively. The differential leukocyte count (DLC) results showed that, the percentage of large lymphocyte (LLYM) was 5.26% ± 3.95%, small lymphocyte (SLYM) was 77.74% ± 11.73%, neutrophil (NEU) was 9.40% ± 7.98%, eosinophil (EOS) was 1.90% ± 2.06% and monocyte (MON) was 5.50% ± 4.00% respectively, and the results of different ages were in Table 2. The RBC of 18 age and 11 age groups showed significant differences with the rest of groups. The haematocrit (HCT) and hemoglobin (HB) of > 30 age group had significant differences with other groups (P < 0.05, Table 2). The WBC of 18 age had significant difference with 4 age group, and they all had significant differences with the rest of groups (P < 0.05, Table 2). The neutrophil and lymphocyte of > 30 age had significant differences with 4 age group, and they all had significant differences with other groups (Table 2). In the quickly development stage of gonad, the average level of HCT was changed from 27.98% ± 6.77% to 39.67% ± 6.01%, the RBC was from 5.34 ± 1.30 × 108/ml to 7.50 ± 1.37 × 108/ml, and the WBC was from 11.15 ± 4.75 × 109/L to 22.00 ± 9.99 × 109/L, they were significantly increased than before (P < 0.05, Fig. 1), the average level of HB was from 74.32 ± 20.69 g/L to 90.71 ± 18.58 g/L and there was no significant difference. The WBC of diseased sturgeons was increased by 90%, which had significant difference with that before (P < 0.05, Fig. 2), and along with the decrease of RBC, HCT and HB. The differential leukocyte count (DLC) of diseased sturgeons changed significantly, primarily neutrophils and monocytes (Fig. 3). It concluded that the immune system of A. sinensis was mainly composed of lymphocytes, granulocytes and monocytes. The hematology of the peripheral blood cells of A. sinensis was different before and after the quickly gonadal development or when they were diseased, it can be used to judge the condition of A. sinensis in time. The results are important to the health assessment and conservation research of A. sinensis.