Porcine astrovirus (PAstV) is a non-enveloped RNA virus in the family Astroviridae and is a small, non-enveloped, single-stranded, positive-sense RNA virus named for its 5–6 pointed star-like morphology. The genome of PAstV varies from 6 to 8 kb and contains three open reading frames (ORFs) encoding non-structural polyproteins (ORF1a), RNA-dependent RNA polymerase (ORF1b), and capsid proteins (ORF2), respectively. Based on the nucleotide similarity of the capsid protein ORF2, PAstV is divided into at least five distinct lineages (PAstV1–PAstV5). With the exception of PAstV3, which is associated with neurological symptoms, other four lineages are associated with diarrhea. PAstVs is mainly transmitted through the fecal-oral route and has a high prevalence in swine herds. It is easily mixed with other diarrhea viruses, resulting in clinical symptoms such as diarrhea in piglets and causing serious economic losses to farms. There has been recombination between human and PAstV in some ORF2 genes, and they are closely related to the evolutionary process. Fecal samples are the main source of virus isolation, and PCR-based assays are the most commonly used diagnostic tool. However, there is currently no available anti-AstV vaccine in any species. Therefore, in-depth study of PAstV plays an important role in public health.