The new species Zagrammosoma dulanense Cao & Zhu, sp. n., from Qinghai Province, China, is described and illustrated. All type specimens were reared from the pupae of Micrurapteryx sophorivora Kuznetzov & Tristan (Lepidoptera: Gracillariidae), a leafmining moth attacking the plant Thermopsis lanceolata R. Br. (Fabaceae). A key to the three known Asian species of Zagrammosoma is provided. All specimens are deposited in the Insect Collection, the Institute of Zoology, Chinese Academy of Sciences, Beijing, China.