Abstract: Influenced by multi-phase thrusting, extensional tectonic movements, and the plastic deformation of mudstone, shale, and gypsum, the deformation of the Biluoco oil shale stratum (BLS) in the Qiangtang Basin is extremely complex. Additionally, controversies surrounding paleontological fossil evidence and isotopic geochronology have severely constrained the understanding of the lithological assemblages and their temporal attribution. In response to the intricate structural deformation of BLS, this study conducted detailed structural observations and profile measurements. Based on the thrust-fold system, the stratum was traced and correlated, dividing into three segments with seven types of lithological assemblages from bottom to top. Zircon U-Pb isotopic testing, along with zircon structure and genetic analysis, was performed on the sandstone of the lower segment and the basalt of the middle segment, yielding maximum depositional ages of 166 Ma and 154 Ma, respectively. Integrating regional context, it is concluded that the age of BLS ranges at least from the Middle Jurassic Bathonian to the Late Jurassic Tithonian, with the top possibly extending to the Early Cretaceous Berriasian. The determination of the age for BLS provides new insights for hydrocarbon exploration in the Qiangtang Basin, as well as for studies on sedimentary tectonic evolution and oceanic anoxic events.