Perfluorooctane sulfonate (PFOS) has emerged as one of the most concerning contaminants in recent years. In the present study, the developmental toxicity of PFOS on zebrafish embryo was tested. The EC50 based on the general morphology score are 78.13 and 76.53 mg/L for 96 h and 120 h, respectively. While the LC50 values for 96 h and 120 h are 79.08 and 70.17 mg/L, respectively. It was found PFOS resulted in the decrease of heart rate of zebrafish embryo, while had some degree of stimulation at 40 mg/L PFOS.