Four species of the genus Prochiloneurus Silvestri, belonging to the family Encyrtidae of Hymenoptera, are reported from China. Among them, P. stenopterus Wang, Huang & Xu sp. nov., which is reared as the hyperparasitoid of Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive mealybug to China, is reported as new to science. A key of the genus is provided for the recognition of the females of Chinese species. Notes on the parasitoid and hyperparasitoid of the mealybug Phenacoccus solenopsis are provided.