Abstract: Haemophilus parasuis were identified by PCR from Hunan province isolates,and used 16S rRNA sequences to reconstruct their phylogenetic relationship. The partial 16S rRNA was amplified from each H.parasuis, and sequences were aligned using the ClustalX 1.81. MP and NJ trees of 16S rRNA were constructed using the software Phylip 3.67 version 4.0 and Mega version 4.0, and ML tree was also constructed using Puzzle version 5.2. Sequence homology analysis was performed using the Megalign program of the software DNAStar version 5.0. The results showed that the lengths of 16S rRNA sequences were 783 bp. The constructed phylogenetic tree revealed that the Hunan isolates and the H. parasuis serovar 05 available in GenBank were clustered in the same clade. The results of the present study provided foundation for further studies of molecular epidemiology of H.parasuis and for diagnosis of the resultant disease.

Key words: H.parasuis; 16S rRNA; phylogenetic relationship