Objective：To elucidate the physiological functions of coenzyme Q biosynthesis protein 4 homolog（COQ4）in mammals by using Coq4 knockout（Coq4^-/- ）mice. Methods：Coq4 global heterozygous mouse models were introduced，and the different genotypes of mice were detected by genomic PCR. The phenotypes，growth，reproduction of Coq4 ^+/- mice were observed and recorded. The morphology and structure of embryonic and placental tissues of wild type（WT）and Coq4^-/- mice were studied by anatomic and histological analyses as well as immunofluorescence assay. Results：Coq4^-/- mice exhibited an impaired gastrulation on embryonic day （E）7.5（E7.5）and were died on E10.5. Morphological analysis showed severely retarded embryonic development with obvious defective placental structures in Coq4^-/- mice，compared with the WT mice. Immunofluorescence analysis revealed that trophoblast cell invasion was diminished in the placenta of Goq4^-/- mice. Conclusion：Knockout of Coq4 gene leads to impaired placenta and gastrula formation in mice. Coq4 is essential for embryonic development.