African swine fever virus (ASFV) causes contagious hemorrhagic disease of pigs with high morbidity and mortality. To identify the molecular characterization of ASFV strains circulating in Guangxi province, southern China, tissue samples collected from domestic pigs that died as a result of severe hemorrhagic disease during 2019-2020 were detected for ASFV, and 66 representative ASFV strains from Guangxi province were genetically characterized by sequence analysis of the C-terminal region of B646L (p72) gene, the complete E183L (p54) gene, the variable region of EP402R (CD2v) gene, the central variable region (CVR) of B602L gene, and the tandem repeat sequence (TRS) within the intergenic region (IGR) between the I73R and I329L (I73R/I329L) genes. Phylogenetic analysis revealed that the ASFV strains from Guangxi province belonged to genotype I and II based on the p72 and p54 genes, and there were eight different tetrameric TRS variants based on the CVR of B602L gene. Phylogenetic analysis of the CD2v gene revealed that these ASFV strains belonged to serogroup IV and VIII. Eight of the 66 strains belonged to genotype I and serotype VIII, and showed deletion of whole MGF505-2R gene. The sequence analysis of the IGR between the I73R/I329L genes showed that IGR II and III variants were co-circulating in Guangxi province. The results indicated that ASFV strains circulating in Guangxi province during 2019-2020 outbreaks showed highly genetic diversity, of which genotype I and II strains, as well as serogroup IV and VIII strains, were simultaneously epidemic, and there existed wild-type strains and naturally gene-deleted strains in the field. This is the first report on the molecular characterization of the ASFV strains circulating in southern China.