Abstract: In order to understand the current epidemic status of classical swine fever （CSF） in Zhejiang，a survey of 18 pig farms suspected of CSF in 8 cities of Zhejiang Province was conducted. The results indicated that CSF cases mainly showed a typical or mild symptom. Most of cases were attributed to outside inducement， such as long distance transport， castration and vaccination， and other kinds of pathogen infection. Majority of cases occurred in pigs under 3 months of age and had a long course of disease. CSFV was detected in some clinical health sows and reproductive problem sows. The detection rates of CSFV， porcine reproductive and respiratory syndrome virus （PRRSV） and porcine circovirus type Ⅱ （PCVⅡ） from 38 specimens suspected for CSF were 47.37%， 44.7% and 23.68%， respectively. The mixed infection rates of PRRSV and CSFV or PCVⅡ and CSFV were 33.3% and 11.1%， respectively. Molecular epidemic investigation results indicated that E2 nucleotide homology of epidemic CSFV strains in Zhejiang compared with Shimen strain， HCLV strains and the attenuated vaccine strains from different manufacturers were 81.2%-83.0%， 83.1%-84.0% and 81.7%-82.6%， respectively， indicating that the epidemic strains of CSFV in Zhejiang was moving away from the vaccine strain and showed genetic diversity.

Key words: CSF, epidemiological investigation, Zhejiang