Abstract: In order to explore the regulation mechanism of the tick salivary glands by blood feeding, and screen vaccine candidates, a EST with poly(A) tail from the subtractive cDNA library of the hard tickHyalomma asiaticum was further studied. 5′ rapid amplification of cDNA ENDS (RACE) were used to clone the full length cDNA. The full length of the gene named P27 is 827 bp and the coding region is from 35 bp to 706 bp. The putative protein of P27 is 27 kDa,and the isoelectric point is 4.22. The structure analysis showed that it contain a cross-membrane region and many activated loci, which suggest its transcript action in cell. Comparison of deduced amino acid sequences showed low homology with reported protein in the database. Expression analysis by RT-PCR revealed that P27 was expressed in salivary gland, shell and midgut of fed tick, but not in the unfed tick, which indicates P27 is induced to express by tick blood feeding.