The Lower Cretaceous deposits in the Mazongshan area of Gansu Province are rich in plant fossils, which are poorly studied. In this paper, detailed morphological and anatomical studies were conducted on the gymnosperm seed fossils collected from the Lower Cretaceous Chijinbao Formation in the Mazongshan area, Gansu Province. The morphological structures are observed by using stereomicroscope and X- ray tomography, and the cuticular micro- structures are observed by using light microscope, fluorescence microscope and Scanning Electron Microscope. The present gymnosperm seed fossils are charactered by elliptical or oval- shaped, smooth or with longitudinal grains on the surface, which is consistent with the fossil genera Carpolithus, and were identified as Carpolithus. Carpolithus is elliptical, oval or spindle- shaped with smooth or ornamental surface. The numerous gymnosperm seed fossils present were identified as Carpolithus mazongshanensis sp. nov. and Carpolithus cf. jidongensis respectively. C. mazongshanensis sp. nov. is oval shaped, beaked apically and rounded basally, with arc- shaped parallel longitudinal grains on the seed surface. The outer stratum corneum cells of the seed coat were elongated; the stratum corneum cells were nearly square or polygon. C. cf. jidongensis is oblong ovate shaped, obtuse apically and narrows gradually at the base, with arc- shaped longitudinal grains on the seed sides. The outer stratum corneum cells of C. cf. jidongensis seed coat are elongated. Based on the contrastive analysis of both morphology and epidermal characters with extant gymnosperm seeds, C. mazongshanensis sp. nov. and C. cf. jidongensis may be closely related to Platycladus.