A singlefactor static acute toxicity test was conducted to study the effects of different concentrations K⁺ and Ca²⁺ in a water body with salinity 10 on the survival rate, oxygen consumption rate, and suffocation point of juvenile Barbus capito. At the K+ concentration 3.78-43530 mg·L-1 and Ca²⁺ concentration 11.01-1535.90 mg·L^-1 (with 117.55 mg·L^-1 of K⁺ and 116.59 mg·L^-1 of Ca²⁺ as the controls), all the juveniles could survive. The 96 h LC₅₀ of high concentration K⁺ and of low concentration Ca²⁺ was 515.01 mg·L^-1 and 5.47 mg·L^-1, respectively. At low concentration K+ (3.75±0.17 mg·L^-1), no significant variations were observed in the oxygen consumption rate and suffocation point of juvenile Barbus capito (P>0.05); at high concentration K⁺ (451.67±10.23 mg·L^-1), the oxygen consumption rate at 48 h had no significant difference with the control (P>0.05), but that at 72 h and 96 h increased significantly (P<0.05), and both the critical and the absolute suffocation points had a significant increase (P<0.05). At low concentration Ca²⁺ (8.87±0.34 mg·L^-1) and high concentration Ca₂ (129010±15.75 mg·L^-1), the oxygen consumption rate presented the same tendency, i.e., increased significantly at 24 h (P<0.05), declined at 48 h, and had no significant difference with the control (P>0.05) at 96 h. Whether at low or at high concentration Ca²⁺, both the critical and the absolute suffocation points of the juveniles increased significantly (P<0.05), as compared to the control. To sum up, the juvenile Barbus capito had stronger tolerance to the K⁺ and Ca²⁺ in water body, especially to the low concentration K⁺ and high concentration Ca²⁺.