A novel actinobacterium, designated strain NEAU-QY2T, was isolated from the leaves of Sonchus oleraceus L. specimen, collected from Wuchang, Heilongjiang Province, China. A polyphasic study was carried out to establish the taxonomic position of this strain. The organism formed single spores with rough surfaces on substrate mycelia. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain NEAU-QY2T belonged to the genus Plantactinospora and formed a monophyletic clade with its closest related strains Plantactinospora endophytica YIM 68255T (99.2 % 16S rRNA gene sequence similarity), Plantactinospora veratri NEAU-FHS4T (98.8 %) and Plantactinospora mayteni YIM 61359T(98.7 %), an association that was supported by a bootstrap value of 90 % in the neighbor-joining tree and also recovered with the maximum-likelihood algorithm. However, DNA-DNA hybridization values between strain NEAU-QY2T and the three closely related strains were below 70 %. With reference to phenotypic characteristics, phylogenetic data and DNA-DNA hybridization results, strain NEAU-QY2T was distinguished from closely related strains and is classified as representing a novel species of the genus Plantactinospora, for which the name Plantactinospora sonchi sp. nov. is proposed. The type strain is NEAU-QY2T (=CGMCC4.7216T=JCM 30345T).