<p>At present, the research on tick malformations is still in its infancy, mainly focusing on the exploration of the abnormal forms, while the research on its molecular level is relatively scarce. In this study, under identical feeding conditions, three deformed adult ticks that occurred occasionally among 320 laboratory-bred <i>Hyalomma anatolicum</i> were selected as the research subjects, three adult ticks with normal morphology were observed and selected as controls by stereomicroscopy and the differences in gene expression between the two groups were analyzed through transcriptome sequencing technology. The results show that morphological identification and photo analysis reveal that abnormal ticks have deformities in limbs and/or mouthparts. Through differential gene analysis, it was revealed that compared with normal ticks, abnormal ticks showed a downward trend in the expressions of ecdysone-related genes of ecdysone-induced protein, cuticle protein and chitinase, detoxification-related genes of detoxification proteases and cytochrome, immune defense-related genes of antimicrobial peptides and antifreeze protein. However, the gene expressions of heat shock protein, serine protease, serine protease inhibitors, etc. showed an upward trend. This study has for the first time discovered that the transcriptome of adult ticks with morphological abnormalities is significantly different from that of normal individuals, suggesting that the dysregulation of gene expression may be related to morphological abnormalities. An in-depth exploration of the key genes in the growth and development of these ticks is expected to provide potential approaches for the development of new anti-tick strategies. Future studies need to further verify the functions of these differentially expressed genes.</p> Graphical abstract <p></p>