Objective To investigate rodents, chigger mites and Orientia tsutsugamushi on mountains and plain in Qing' an county. Methods Small mammals were trapped by snap traps in September, 2013. Rodents and their ectoparasites were collected and identified morphologically. Then the rodents were dissected under sterile conditions. DNA was extracted from the spleens, nested-PCR was performed to amplify and sequence the 56 kD type-specific antigen gene of O. tsutsugamushi from all samples collected in this area. Results A total of 107 small vertebrates including 9 species were captured. Apodemus agrarius was the predominant species in outdoor rural settlements and farmland. While Rattus norvegicus and Mus musculus were the predominant in indoor environment. Apodemus agrarius and Ap. peninsulae were the predominant species in forest areas. A total of 1 164 chigger mites were collected from small mammals, including Neotrombicula gardellai, Leptotrombidium orientalis, N. japonica, and L. subintermedium. Chigger mite index on M. rufocanus was highest (65.50), then T. triton (58.13), C. rutilus (22.86) and Eutamias sibiricus (24.00). No chigger mites were found in rural settlements and farmland far from forest. Orientia tsutsugamushi was detected from T. triton and Ap. peninsulae by nested-PCR. Conclusion The composition of the small mammals and chigger mites species is similar to those in the north of Northeast China. Orientia tsutsugamushi was firstly detected in rodents in the county. Therefore Qing' an is an new natural focus of scrub typhus and human infection should be investigated in the future.