[Aim] In recent years, the aquaculture of redclaw crayfish has significantly increased. The aim of this study is to understand the ammonia-N and nitrite-N tolerance of different life stages of red claw crayfish to improve the survival rate and promote the redclaw crayfish production in aquaculture.[Method] The acute toxicity of ammonia-N and nitrite-N on juvenile and subadult redclaw crayfish was tested, and the half lethal concentrations (LC₅₀) and safe concentrations (SC) under 24~25℃ and pH 7.9~8.0 were determined.[Result] The LC₅₀s of total ammonia-N for juvenile crayfish at 24 h, 48 h, 72 h and 96 h were 188.0, 136.15, 104.67 and 88.00 mg·L^-1, and the SC was 8.80 mg·L^-1. The LC₅₀s of total ammonia-N for subadult at 24 h, 48 h, 72 h and 96 h were 344.01, 270.46, 205.15 and 167.68 mg·L^-1, and the SC was 16.77 mg·L^-1. The LC₅₀s of non-ionic ammonia for juvenile at 24 h, 48 h, 72 h and 96 h were 10.16, 7.35, 5.65 and 4.75 mg·L^-1, and the SC was 0.48 mg·L^-1. The LC₅₀s of non-ionic ammonia for subadult at 24 h, 48 h, 72 h and 96 h were 18.58, 14.60, 11.08 and 9.05 mg·L^-1, and the SC was 0.91 mg·L^-1. The LC₅₀s of nitrite-N for juvenile at 24 h, 48 h, 72 h and 96 h were 46.76, 33.88, 27.97 and 22.81 mg·L^-1, and the SC was 2.28 mg·L^-1. The LC₅₀s of nitrite-N for subadult at 24 h, 48 h, 72 h and 96 h were 77.56, 59.33, 45.41 and 37.48 mg·L^-1, and the SC was 3.75 mg·L^-1.[Conclusion] The tolerance of redclaw crayfish to ammonia-N was stronger than nitrite-N, and the tolerance of subadult to ammonia-N and nitrite-N was stronger than that of juvenile.