A new species of anaxyelid wood wasp genus Orthosyntexis (Syntexinae) is described from mid-Cretaceous (lower Cenomanian) amber found in the Kachin State of northern Myanmar. The new taxon can be distinguished by: antenna with swollen scape; 14 flagellomeres; forewing with Sc, 1r-rs and 2rs-m absent; 1-Rs shorter than 1-M and proclival; 2Rs + M present but short; and 3r-m being remarkably curved. This evidences a second anaxyelid species (represented by a male individual) in Kachin amber insect assemblage, and adds to the morphological diversity of the family. A key to the species of Orthosyntexis is provided.Ziqing Wang [1554245607@qq.com], Institute of Geology and Paleontology (College of Education), Linyi University, Shuangling Road, Linyi 276000, PR China; De Zhuo [405425109@qq.com], Beijing Xiachong Amber Museum, Shuanghe Middle Road, Beijing, 100023, PR China; Han Wang [hanwang@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, East Beijing Road, Nanjing 210008, PR China; Jun Chen [rubiscada@sina.com], Institute of Geology and Paleontology (College of Education), Linyi University, Shuangling Road, Linyi 276000, PR China; Haichun Zhang [hczhang@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, East Beijing Road, Nanjing 210008, PR China; Alexander P. Rasnitsyn [rasna@online.ru], Palaeontological Institute, Russian Academy of Sciences, Moscow, 117647, Russia, and The Natural History Museum, London SW7 5BD, UK; Yan Zheng* [zhengyan536@163.com], Institute of Geology and Paleontology (College of Education), Linyi University, Shuangling Road, Linyi 276000, PR China.