Currently, various antimitotic inhibitors applied in tumor therapy. However, these inhibitors exhibit targeted toxicity to some extent. As a motor protein, kinesin family member 18A (KIF18A) is crucial to spindle formation and is associated with tumors exhibiting ploidy-specific characteristics such as chromosomal aneuploidy, whole-genome doubling (WGD), and chromosomal instability (CIN). Differing from traditional antimitotic targets, KIF18A exhibits tumor-specific selectivity. The functional loss or attenuation of KIF18A results in vulnerability of tumor cells with ploidy-specific characteristics, with lesser effects on diploid cells. Research on inhibitors targeting KIF18A with ploidy-specific lethality holds significant importance. This review provides a brief overview of the regulatory mechanisms of the ploidy-specific lethality target KIF18A and the research advancements in its inhibitors, aiming to facilitate the development of KIF18A inhibitors.