A strain of mink infectious enteritis virus that was isolated from the east district of China can be bred on FK cell. Concentrated viruses were purified by using Sepharose-4B chromatography. The size of the virus was about 20-22 nm by electron microscope. Viral nucleic acid was extracted from pure virus by using SDS-protease K-Phenol. Tests with diphenylamine, acridine orange and the curve of thermal dentuation, etc. showed that the virus had a single-stranded DNA. The molecular weight of the ssDNA was from 1.5 x 10(6) to 2.0 x 10(6) determined by length of the virul nucleic acid.