A well-preserved radiolarian assemblage is described from argillaceous limestone of the Wulalike Formation in the Northwest Ordos Basin, North China. A total of nine species of seven genera are described, including Inanigutta gansuensis, I. quadrispinosa, I. complanata, Inanibigutta pinglianensis, Oriundogutta bella, Triplococcus acanthicus, Haplentactinia juncta, Syntagentactinia pupila n. sp., and Kalimnasphaera maculosa. Three-dimensional X-ray micro-computed tomography is used to make a detailed examination of the new species. This is the first documentation of radiolarian fossils from the Wulalike Formation, which contributes to better understanding of the features of Ordovician radiolarian faunas and facilitate stratigraphic correlation and subdivision in the Ordos Basin.