Provided are a nanoporous organic polymer and preparation method thereof, and its application for catalyst. More particularly, provided is a nanoporous organic polymer composite comprising a mesoporous molecular sieve having micropores within mesopore walls, and an organic polymer impregnated within the micropores of the molecular sieve and coated on the wall surfaces of the molecular sieve. Also, provided is a method for preparing a nanoporous organic polymer composite comprising preparing a mesoporous molecular sieve having micropores within mesopore walls; impregnating an organic monomer diluted in solvent into the molecular sieve; and polymerizing the molecular sieve impregnated with the organic monomers to form organic polymers within the micropores and on the wall surfaces of the mesoporous molecular sieves. Further, provided are properties of catalytic reaction of the material as applicable representative examples of the nanoporous organic polymer.