Abstract: The Upper Cretaceous Daxingzhuang Formation in western Liaoning is mainly distributed in Jinzahou and Yixian and also outcrops sporadically in the Boluochi ,Chaoyang,and Jianguo,Fuxin.Ex-cept in the Fuxin area where it is composed of intermediate-basic lavas and pyroclastic rocks,in other ar-eas it consists of intermediate-acid and acid lavas,lava-clastic rocks,pyroclastic rocks,pyroclastic-sedi-mentary rocks and subvolcanic rocks.It lies unconformably on the Lower Cretaceous Yixian,Jiufutang and Sahai Formations and disconformably on the Cretaceous Sunjiawan Formation.Its K-Ar age is80.83Ma ,indicating a Late Cretaceous age.This phase of volcanism is characterized by alternating explosion and out-pouring.In the late phase subvolcanic rocks were in truded.The activity was weak and the distribution of the subvolcanic rocks is limited.