Ordovician reservoirs in northern Tarim Basin are carbonate karst fracture-cave reservoirs with large spatial scale differences, structural changes and strong heterogeneity. With the continuous deepening of exploration, the development target is transferred from large-scale karst cave to small-scale fracture cave and pore aggregate. The effective identification and fine characterization of such reservoirs, which are mainly characterized by random reflection, continuous trough reflection and other seismic reflection characteristics, is the key to the continuous increase of production. Based on seismic numerical simulation and physical model forward modeling, a variety of seismic characterization methods and seismic attribute sensitivity analysis are carried out for small-scale fracture-cave reservoirs. For the small-scale fracture-cave bodies with disordered weak reflection, the spatial distribution of this type of reservoir can be well reflected by using the transverse change rate of amplitude curvature. For the small-scale dissolved pore and fractured reservoirs, the reflection intensity tuning cumulative frequency attenuation attribute can be used to describe the boundary profile of the reservoir effectively. The prediction results of the actual data are consistent with the real drilling characteristics and imaging logging data, which verifies the effectiveness of the characterization method of small-scale fracture-cave reservoir.