Abstract: In order to get a clear understanding of nucleotide homologous relation between isolated strains in North-east area and other reference strains of Orientia tsutsugamushi,partial sta56 gene of the isolaled strains were amplified by PCR.Amplified-fragment of isolated strains HCAa9202 and HCM 9501 were sequenced.Meanwhile,a homologous comparison was made with the reference strains of known sequence.Results showed that a specific amplified-fragmants of the Orientia T sutsugamushi strains isolated in Northeast ar ea was observed in the fields of 320~332bp,while 2~3 amplified-fr ag mant were observed seperately in the strains of MSAa9302 and MSAa9304 in the same fields.The nucleotide homolog y between the strains of HCAa9202,HCM 9501 and the 6 Orientia T sutsugamushi strains of known sequence was 67.72%~83.18%.Both isolated strains have a high nucleotide homology with Gilliam strain.