The genome of Transmissible gastroenteritis virus (TGEV) displays genetic diversity especially in gene 3 region. Sequence and comparative analysis of 3a and 3b genes of eight Chinese field strains with reference TGEV strains indicated that these strains shared 87.0-100% and 51.5%-100% identities at the nucleotide level, respectively, and 86.1%-100% and 66.2%-100% identities at the amino acid level, respectively. Moreover, in one of the strains (CH/SDQ/08), a 51 nt deletion in the gene 3 region was found. Phylogenetic analysis showed that the eight Chinese strains were more closely related to TGEV strains H165, H16, Miller M6, Miller M60, TS, and CHV than to other reference strains. In addition, this study indicated the presence of different TGEV strains within the same pig herds in China.