Abstract:Classical swine fever (CSF)， caused by the CSF virus， is a highly contagious swine disease leading to significant economic losses for the pig industry worldwide. CSF is recognized as one of OIE notifiable diseases. Phylogenetic analysis based on the nucleotide sequences of viral gene fragments shows that CSFV isolates can be divided into three genotypes (genotypes 1~3)， which are further separated into 3 to 4 subgenotypes (1.1~1.4， 2.1~2.3 and 3.1~3.4). The temporal-spatial dynamics， host factors and control strategies have significant impact on the genetic diversity， distribution and evolution of CSFV isolates. It has been demonstrated that in Europe， where culling of infected pigs as control strategy was performed， genotype 1 isolates were switched to genotype 2 since 1970s， while CSF isolates circulating in wild boar population remain to be subgenotypes 2.2 and 2.3. In Latin America， genotype 1 viruses are only isolates circulating in this region. Furthermore， the major genotypes of CSF viruses in Korea and Taiwan were switched from genotype 3 to subgenotype 2.1 since the end of 20th century. The latter along with subgenotype 1.1 are predominant in mainland China. As the increasing number of CSF viruses detected in recent years， subgentoype 2.1 has been further classified into 3 sub-subgenotypes (2.1a~2.1c) and all of them have been found present in China. Most recent studies showed that nucleotide mutation has been recognized as the key factor to drive CSFV evolution. Moreover， homologous recombination and quasispecies also play important roles in the adaptation of CSFV to the environment. In conclusion， studies on genetic variation， genotype distribution and evolution of CSF viruses may provide useful insights into the control and prevention of this devastating disease.