Oomyzus spiraculus Song, Fei & Cao sp. nov. (Hymenoptera, Eulophidae) is described and illustrated as a gregarious larval-pupal endoparasitoid of Coccinella septempunctata L. (Coleoptera, Coccinellidae). Differentiation between O. spiraculus and its similar species is discussed and a key to differentiate the female and male of these species is provided. DNA barcodes of O. spiraculus and O. scaposus are analyzed and compared.