Abstract: Tetrastichus howardi species group in Tetrastichus Haliday belongs to Hymenoptera order, Eulophidae family, Tetrastichinae genus. Recognition feature of the species group and geographic distribution, hosts, feeding habits and biological characteristics of 8 parasitic wasps in Tetrastichus howard species group were introduced in detail. Research progresses on biology, behavior, artificial production and releasing technique of two important parasitoids, T. howardi and T. nigricoxae, were reviewed systematically, and that have important implications for future study on these parasitoid distributed in China. The common character and difference of these parasitoids biology were discussed and research direction and application strategy of controlling poplar defoliator to use T. nigricoxae in the future were also explored in this paper.