Unlike conventional clastic rock reservoirs, paleokarst cavernous carbonate reservoirs are special in origin and distribution, which causes the inapplicability of isochronal modeling and facies-controlled modeling. Taking the Ordovician reservoir in the Tahe Oilfield, Tarim Basin as an example, based on identification of cave reservoir types, an original 3D modeling method combining the constraint of faults, karst zones, and seismic impedance was proposed, and a 3D karst reservoir distribution model was built. A Gaussian Kriging simulation method was used and the three kinds of constraint were integrated by the data fusion principle. The results compare well with the cumulative production data.