Under the conditions of water temperature (28±0.2)℃, salinity 29.8±0.2, pH  8.0±0.2 and dissolved oxygen 6.0mg/L, juvenile shrimp Marsupenaeus japonicus with body length of (49.28±4.79) mm was put in a 100 L white bucket with 20 L of water. NaNO2 (analytical pure) was dissolved in fresh seawater to prepare 2 000 mg/L mother liquor and make the concentration of nitrite (NO2--N) in the water of the test group 151.36, 239.88, 380.19, 602.56 and 954.99 mg/L. The acute toxicity of NO2--N to juvenile shrimp Marsupenaeus japonicus was studied by hydrostatic toxicity test. The results showed that the NO2--N toxicity was positively correlated with the concentration and stress period, the mortality rate of Marsupenaeus japonicus increased with the increase of NO2--N concentration at the same time, and the mortality rate of shrimp increased with time at the same concentration. The lethal concentration (LC50) of NO2--N to Marsupenaeus japonicus was 1806.100 mg/L in 24 h, 970.939 mg/L in 48 h, 780.050 mg/L in 72 h and 427.391 mg/L in 96 h, with safe concentration of 42.739 mg/L. The lethal time (LT50) was 120.008 h at concentration of 151.36, 111.954 h at 239.88, 94.207 h at 380.19, 78.810 h at 602.56, and 60.102 h at 954.99 mg/L. The test showed that the concentration of NO2--N should be controlled below 42.739mg/L in culture water of Marsupenaeus japonicus.