Three Gram-stain-positive, catalase-negative, α-haemolytic, chain-forming and coccus-shaped microorganisms (strains Z15T, Z1 and Z2) were isolated from feces of Tibetan antelopes collected from the Qinghai–Tibet plateau, PR China. The results of 16S rRNA gene sequence studies indicated that Z15T shared 94.5, 93.1 and 92.2 % similarity with Streptococcus pantholopis DSM 102135T, Streptococcus ursoris NUM 1615T and Streptococcus dentapri NUM 1529T, respectively. rpoB and groEL-based sequence analysis of our three novel isolates revealed interspecies divergence of 16.7 and 14.3 % from Streptococcus pantholopis DSM 102135T. The genomic DNA G+C content of Z15T is 42.48 mol%. Z15T has an average nucleotide identity (ANI) value of 81.19 % with S. pantholopis DSM 102135T and a DNA–DNA relatedness value of less than 70 % in the in-silico DNA–DNA hybridization (isDDH) with other species of genus Streptococcus deposited in the GenBank database. A whole-genome phylogenetic tree based on 246 core genes of 78 genomes of members of the genus Streptococcus indicated that Z15T represents a member of genus Streptococcus but one well separated from the currently recognized species. Z15T contains C18 : 1ω7c (25.5 %), C18 : 1ω9c (19.6 %), C16 : 0 (17.5 %) and C16 : 1ω9c (13.3 %) as its major cellular fatty acids. According to the morphological, biochemical and molecular phylogenetic features of the three novel isolates, they represent a novel species of the genus Streptococcus , and Streptococcus chenjunshii sp. nov. is thus proposed. The type strain is Z15T (=CGMCC 1.16529=DSM 106182).