A new roachoid species, Necymylacris sinica n. sp., is described from the lower Permian (Asselian, Cisuralian) Shanxi Formation in the Qinshui Basin, North China, based on a partially preserved forewing. This discovery represents the second record of the family Necymylacridae in China and the first from the Shanxi Formation in the Qinshui Basin. The holotype was found co-preserved with a low-diversity assemblage of 14 plant taxa (among 263 fossil-plant specimens), dominated by cordaitalean leaves (Cordaites principalis and Cordaites sp.) and pteridophytes (morphogenera Pecopteris spp.), with lesser proportions of sphenophytes, lycophytes, and seed ferns. The fossil flora and regional geological data suggest a warm, humid, low-diversity forest ecosystem in non-seasonal climates of palaeotropical Cathaysia. Evidence of plant-insect interactions, such as margin feeding, hole feeding, piercing and sucking, galling, oviposition, and seed predation, reveals that a diverse array of herbivorous insects with varying feeding strategies inhabited the Permian palaeoforest of the Qinshui Basin. These findings provide new information about the ecological complexity of early Permian palaeotropical forests during the peak of the Late Paleozoic Ice Age and new insights into the palaeoecology and biodiversity of Cathaysia during this period. The study underscores the importance of historical collections, such as those at the Swedish Museum of Natural History, in advancing our understanding of ancient ecosystems. Taxonomically, Stephanotermopsis rodendorfi Laurentiaux, 1966 is transferred into the family Necymylacridae.