The studies have been carried out in laboratory on the effect of dyeing, electroplating, pesticide effluents and their intermixture on embryos of lefteye flounder ( Paralichthys olivaceus ). The main toxic substances in dying effluent are aniline ( 20 mg/L ) and phenol ( 24 mg/L ). The main toxic substances in electroplating effluent are Zn ( 1 970 mg/L ), Cu ( 9 mg/L ) and Pb ( 7.5 mg/L ). The main toxic substances in pesticide effluent are monocrotophos and phosphite. The test results indicate that the lowest concentrations of dyeing, electroplating, pesticide effluents and their intermixture, having significant effect on the hatch rate and development of P. olivaceus embryos, are 0.5%, 0.15%, 0.25% and 0.25%, respectively; and the incipient LC50 of dyeing, electroplating, pesticide effluents and their intermixture are 3.38% ( ~ 2.29%3.87%, )0.81% ( ~ 0.71%0. 92% ), 1.57% ( ~ 1.37%1.82% ) and 1.48% ( ~1.24%1.76% ). Based on the incipient LC50 values, the toxicity sequence of the three industrial effluents is in the order of electroplating effluent > pesticide effluent > dyeing effluent.