The palaeo-subterranean river has strong heterogeneity and complex spatial structure，which bring difficulties in understanding on facture-cave structure characteristics of palaeo-subterranean river in the western Tahe Oilfield and its controlling factors. To solve these problems，the well-seismic calibration technique and the spectral decomposition technique were utilized to identify and characterize the palaeo-subterranean rivers systemically in the western Tahe Oilfield.Results show that there are four major palaeo-subterranean rivers in the Ordovician carbonate rocks in the western Tahe Oilfield，presenting as complex reticular or dendrimer structure in the plane. From the dynamic and static data of drilling wells and well-seismic calibration，there are two types of horizontal distribution pattern for the karst caves of the palaeosubterranean rivers，which are the ribbon-like cave with continuous distribution and the block-like cave with scattered distribution. In the vertical，it can be divided into three types from top to bottom：unfilled cave，sand and mud filled cave and breccia filled cave. The seismic reflection of favorable fracture-cave reservoirs in the seismic section is characterized by the first trough and peak under the reflection of middle-upper Ordovician top surface in“string”. The Palaeostructural form，fracture system and open entrances control the morphology of palaeo-subterranean rivers and the structural features of fracture-cave reservoirs. As the fault system plays a constructive role in the hydrocarbon charge，the development areas of the palaeo-subterranean river matching well with faults are favorable targets for hydrocarbon enrichment.