Objective：To observe the incidence and ultrastructure of folic acid，resveratrol and α-naphthoflavone antagonize 2，3，7，8-tetrachlorodibenzo-p-dioxin（TCDD）-induced fetal mice cleft palate. Methods：On gestation day 10（GD 10），40 pregnant mice were randomly assigned to 5 groups. TCDD group（TCDD 28 μg/kg），control group（corn oil 0.1 ml/kg），folic acid group（folic acid 10 mg/kg+TCDD 28 μg/kg），resveratrol group（resveratrol 50 mg/kg+TCDD 28 μg/kg），α-naphthoflavone group（α-naphthoflavone 5 mg/kg+TCDD 28μg/kg） were gavaged. Incidences of cleft palate of each group were observed on GD17.5. Another 15 pregnant mice were randomly divided into five groups，the same as above. The head coronal sections of the fetal mice were prepared on GD 13.5，14.5，15.5，observed by scanning electron microscopy（SEM）. Results：Incidences of cleft palate were 92.86% in TCDD group，0% in control group，73.08% in folic acid group，74.51% in resveratrol group，65.52% in a-naphthoflavone group. There were significant differ－ences of cleft palate incidence in folic acid，resveratrol and α-naphthoflavone groups compared with that in TCDD group（P<0.05）. The embryonic palatal cells in TCDD group gradually ruptured and shrinkaged and filopodia disapperaed；the filopodia in the surface of the smooth cells gradually increased，extended and continued until the end of the palatal fusion in contral，folic acid，resveratrol，α-naphthoflavone groups. Conclusions：Folic acid，resveratrol and α-naphthoflavone can restore the ultrastructure of mice embryonic palatal cells and antagonize TCDD-induced cleft palate.