Abstract: Under the water temperature of 29 ℃, we studied the tolerance of Hemifusus tuba juvenile at shell height (11.3±0.11) mm to nitrite at different pH and salinity. The result shows that the toxicity of nitrite to H.tuba juveniles is greater when pH and salinity are lower. When pH is 6.7, 7.3, 8.0 and 8.8, the 96 h LC₅₀ of nitrite with 95% confidence limit to the juveniles is 188 mg·L^-1(167~213 mg·L^-1), 213 mg·L^-1(195~231 mg·L^-1), 254 mg·L^-1(231~271 mg·L^-1) and 304 mg·L^-1 (284~321 mg·L^-1); correspondingly, the safe concentration (SC) of nitrite to the juveniles is 18.8 mg·L^-1, 21.3 mg·L^-1, 25.4 and 30.4 mg·L^-1, respectively; SC at pH 8.8 is 1.6 times that at pH 6.7. The 96 h LC₅₀ with 95% confidence limit of nitrite to juveniles is 151 mg·L^-1(138~178 mg·L^-1), 171 mg·L^-1(159~192 mg·L^-1), 265 mg·L^-1(246~282 mg·L^-1) and 296 mg·L^-1 (278~323 mg·L^-1) when salinity is 16, 19, 23 and 28; correspondingly, the SC is 15.1 mg·L^-1, 17.1 mg·L^-1, 26.5 mg·L^-1 and 29.6 mg·L^-1, respectively; SC at the salinity of 28 is nearly 2 times that of 16.