Diomorus aiolomorphi Kamijo (Hymenoptera: Torymidae) is an inquiline of gall maker Aiolomorphus rhopaloides Walker (Hymenoptera: Eurytomidae). They are of significant economic significance and predominantly inhabit bamboo forest. So far, only four scaffold-level genomes have been published for the family Torymidae. In this study, we present a high-quality genome assembly of D. aiolomorphi at the chromosome level, achieved through the integration of Nanopore (ONT) long-read, Illumina pair-end DNA short-read, and High-through Chromosome Conformation Capture (Hi-C) sequencing methods. The final assembly was 1,084.56 Mb in genome size, with 1,083.41 Mb (99.89%) assigned to five pseudochromosomes. The scaffold N50 length reached 224.87 Mb, and the complete Benchmarking Universal Single-Copy Orthologs (BUSCO) score was 97.3%. The genome contained 762.12 Mb of repetitive elements, accounting for 70.27% of the total genome size. A total of 18,011 protein-coding genes were predicted, with 17,829 genes being functionally annotated. The high-quality genome assembly of D. aiolomorphi presented in this study will serve as a valuable genomic resource for future research on parasitoid wasps. The results of this study may also contribute to the development of biological control strategies for pest management in bamboo forests, enhancing ecological balance and economic sustainability.