Palaeokarst cave reservoir is a kind of special carbonate reservoir which is remoulded, and development of this reservoir is complex, having strong heterogeneity. It’s significant for the 3D quantitative characterization, numerical simulation, reserve calculation etc. to carry out the modeling of palaeokarst cave reservoir. Through the analysis of objective reality of Ordovician palaeokarst cave reservoir in the Tahe oilfield, several key steps in reservoir modeling, such as modeling strategy, simulation randomness control and mathematical algorithm etc. were discussed. And taking the Ordovician reservoir of the 4th block in the Tahe oilfield as an example, under the geological framework of vertical karst zoning and planar paleogeomorphic division, based upon the borehole data, optimizing wave impedance and coherence attribute which can reflect development probability of caves as cross well constraints, the 3D geological model of palaeokarst cave reservoir is built by using the method of collaborative sequential indicator simulation with a trend to integrate multi information, and thought of local variogram setting is proposed and achieves good results.