The present invention provides a montmorillonite/ZSM-5 molecular sieve composite material and its preparing method. The montmorillonite/beta molecular sieve composite material is prepared by evenly mixing montmorillonite with ZSM-5 molecular sieve gelatin, then processing home position crystallization, and via filtering, washing and drying. The composite material have structure characteristics ofthe montmorillonite and the molecular sieve at the same time, the montmorillonite and the molecular sieve are alternative. The synthetic montmorillonite/ZSM-5 molecular sieve have characteristics of small crystal grain molecular sieve by controlling the synthetic course and the conditions. The preparing method is simple, the easily separating, the molecular sieve composite material has better water-heat stability. The composite material are mainly used for all kinds of catalysts and absorption agents, especially the preparing of hydrogenation catalyst.