The Zhangwu-Heishan area is located in the east of the Fuxin-Yixian basin. Besides the Quaternary soil, the study area is mostly covered with volcanic rock. The horizon and age of volcanic rock play an essential role in understanding fossil beds, structures, and sedimentary evolution of West Liaoning Province and coal seeking. During this work, 11 volcanic rock samples were measured by SHRIMP U-Pb isotope analysis. Based on the reported data on the age of the Mesozoic volcanic rock in West Liaoning Province, in combination with new measurement data, Cretaceous volcanic activities in West Liaoning Province can be divided into five stages, namely 132±1 Ma, 126±1 Ma, 122±2 Ma, 115±2 Ma, and 100±5 Ma. Based on statistical results, this paper concluded that the thinning time of the crust in Northeast China is from 132±1 Ma to 115±2 Ma.