In the field of zoology, blood research is important in many aspects such as animal health, disease treatment, and biodiversity conservation. The continuous advancement of molecular biology technologies, particularly the application of single-cell transcriptome sequencing, has greatly promoted blood research in zoology. This paper reviews the application of single-cell transcriptome sequencing in blood research in zoology and analyzes current challenges and future development trends, aiming to expand the application of this technology in animal science. This review shows that the application of this technology in blood research in zoology is limited at present. This technology is mainly applied in invertebrate insects and crustaceans and less in vertebrates. The research content mainly focuses on blood cell mapping and description and immune defense and response.