Abstract: The basic intermediate subvolcanic rocks from northern Chifeng generated at the end of early Permian epoch to the beginning of late Permian epoch yield U Pb concordant ages of 275.3±4.2 Ma. These subvolcanics, in which basalt, basaltic andesite and andesite are dominant, are petrochemically of calc alkaline affinity of subalkaline series and sodic type, and tend to have moderate low total REE, being LREE enriched. The distribution patterns of REE are manifested as some right sloping flat curves with slight positive negative Eu anomalies. The chondrite normalized plots of transitional elements take “W”shape in general. The initial value of Sr is 0.705 398, implying a deep source. From the above it is suggested that the volcanic series was formed in a tensional state at the isostatic readjustment stage after the intense middle Vriscan orogeny.