Mesopolobus quadrimaculatus Dzhanokmen (Hymenoptera: Pteromalidae) is recorded for the first time from China and outside of Kazakhstan. It was reared from galls of Stefaniola sp. (Diptera: Cecidomyiidae) on black saxaul, Haloxylon ammodendron (C.A.Mey.) Bunge ex Fenzl and white saxaul, H. persicum (Bunge ex Boiss. & Buhse) (Chenopodiaceae) in Beishawo Desert in Fukang, Xinjiang Uyghur Autonomous Region, China.Provided are its illustrated redescription and diagnosis, which was not included in the original description, as well as data on the distribution and biology of this interesting, little known species. Mesopolobus deserti Dzhanokmen, which is also newly recorded from China, was swept on both H. ammodendron and H. persicum at the same site as M. quadrimaculatus. Besides M. quadrimaculatus, seven other parasitoids were also reared from stem-galls of Stefaniola sp. on both Haloxylon ammodendron and H. persicum. However, the relationships between these seven parasitoids and the gall inducer need further study.