Multicellular organisms have many cell types and are complex, and heterogeneity is common among cells. Single-Cell RNA Sequencing (scRNA-SEQ) is a new technique for studying the transcriptional activity of a single cell that is still in its early stages of development. It generates transcriptional profiles from thousands of parallel cells to reveal the differential expression of individual cell genomes. They reflect the heterogeneity between cells to identify different cell types and form cell maps of tissues or organs, which play an essential role in biology and clinical medicine. Based on the introduction and comparison of the scRNA-SEQ sequencing platform, this paper focuses on the application of scRNA-SEQ in the exploration of cell types in the nervous system and immune system and summarizes the research results of the combination of scRNA-SEQ and spatial transcriptome technology.