The genus Ismarus Haliday, 1835 from China is revised for the first time. Three species from Oriental region of China are described and illustrated as new species: Ismarus longus sp. n., Ismarus nigritrochanter sp. n. and Ismarus parvicellus sp. n., with two species: Ismarus dorsiger (Halidy, 1831) and Ismarus halidayi Foerster, 1850 are newly recorded from Chinese fauna. A key to the Chinese species is provided. All type specimens are deposited in the Hymenoptera Collection of South China Agricultural University, Guangzhou (SCAU).