This paper deals with the toxic effects of NH 3 N and NO - 2 N on Penaeus vannamei larvae and Penaeus japonicus larvae. The 24h, 48h,72h, 96h Lc 50 values of NO - 2 N and NH 3 N for the two kinds of larvae were obtained,and the Cs of NO - 2 N and NH 3 N for the two kinds of larvae were obtained,The Cs of NH 3 N for Z,M,and P of the two kinds larvae were 0.078 and 0.047,0.077 and 0.060,0.048 and 0.138 mg/L;the Cs of NO - 2 N for Z,M,and P of the two kinds larvae were 0.56 and 1.08,0.77 and 0.45,2.57 and 2.06 mg/L respectively.