Abstract: Fracture-caved reservoirs in Ordovician carbonate rocks are the main oil and gas reservoirs in Tahe oilfield and the collapse resulted from the subsidence of ancient cave systems is one of the important types of the late karst reformation. Using the data of core, conventional logging, imaging logging, seismic reflection configuration and production performance, the paper analyzes and studies the identification method and the genesis of the collapse in carbonate rocks, presents a set of identification methods applicable to the karst collapses of fracture-caved reservoirs and establishes the corresponding identification criteria for them. Based on the genetic analysis, the karst collapses in Tahe oilfield can be classified into 3 genetic types including fracture induced collapse, overlying stratum load collapse and late-stage hypergene karst collapse. The statistics of 122 collapses of the fracture-caved reservoirs in Tahe oilfield show that the late-stage hypergene karst collapse has the greatest potential for oil and gas development due to the developed fractures and caves within the reservoir.