The invention discloses a different topological structures coexistent composite molecular sieve. The composite molecular sieve is characterized in that an FAU topological structure and an MWW topological structure coexist, the composite molecular sieve has a core-shell structure, the core is the FAU topological structure, and the shell is the MWW topological structure. The composite molecular sieve is prepared through direct crystal transformation of a molecular sieve with the FAU topological structure.