Abstract: The volcanic rocks from Hanxia and Hongliuxia in Jiuxi basin are considered to be resulted from Cenozoic tectonic events．Hanxia volcanic rocks ocurr among the layers of Xiagou Formation，Xinminbao Group of the Early Cretaceous age，and have vesicular and amygdaloidal structures and distinct characteristics of underwater extrusion．These volcanic rocks ale characterized by lower SiO2 and K2O+Na2O，but relatively higher K．ΣREE in these rocks are(212～237)x 10-6．The chondrite-normalized REE patterns are smooth and right-inclined，with weak Ce anomaly and without Eu anomaly．On the primive mantle．normalized spidergrams，all the incompartible trace elements are enriched，especially LILE. There occur Nb and Ta negative anomalies，but still，compared with the primitive mantle，Nb and Ta ale not depleted. These characteristics indicate that the source of the volcanic rocks is the enriched manlte．The REE and trace elements characteristics of the Hongliuxia trachybasalts are very similar to those of Hanxia volcanics．which implies a possible common source．The tectonic setting of the volcanic rocks in Jiuxi basin is confirmed to be continental rifling by using several geochemical diagrams for basalts．This is in accordance with the structural characteristics of lower Cretaceous and the thermal history of Jiuquan basin group．Study on volcanic rocks in Jiuxi basin is significant to deepen the understanding of tectonic evolution of the basin and make clear the tectonic framework of the western China in the Mesozoic．