A new ionizing-radiation resistant strain WGR702 was isolated from arid soils which had been radiated. The strain WGR702 was Gram-positive and coccus, the diameter of the cell was 1.5 μm~2.5μm.The strain WGR702 was pink-pigmented, motile, facultative anaerobe and non-spore forming. The range temperature and pH for strain WGR702 growth were 10℃~35℃ and pH 5.0~10.0 respectively. The strain WGR702 had a G+C content of 60.5 mol%. UV and gamma radiation survival curves showed the strain WGR702 had highly ionizing-radiation resistant. Phylogenetic analysis of the 16S rDNA gene sequences (EU315117) showed 94.79%~98.53% similarities with other recognized Serratia species. Primary characteristics that distinguish isolate WGR702 from the species of genus Serratia include the cells are spherical and Gram-positive. Based on the phenotypic, biochemical and physiological characteristics differences it is proposed that the new isolated strain WGR702 might be classified as a novel species of Serratia.