A novel aerobic streptomycete, strain SCSIO 01248T, was isolated from a sample of deep-sea sediment collected from the northern South China Sea, at a depth of 1632 m. This isolate formed yellow-white substrate mycelium and grey-white aerial hyphae. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SCSIO 01248T was most closely related to Streptomyces radiopugnans R97T (98.8 % sequence similarity), S. macrosporus NBRC 14748T (97.5 %) and S. megasporus NBRC 14749T (97.3 %). The novel strain could, however, be readily differentiated from S. radiopugnans DSM 41901T on the basis of some physiological and cellular chemical characteristics; the level of DNA-DNA relatedness between these two strains was only 40 %. Based on phylogenetic and phenotypic evidence, strain SCSIO 01248T represents a novel species, for which the name Streptomyces nanhaiensis sp. nov. is proposed. The type strain is SCSIO 01248T (=DSM 41926T=KCTC 19401T=CCTCC AA 208007T).