The invention discloses a porous graphene/molecular sieve composite film acid catalyst, and a preparation method and applications thereof. According to the preparation method, synthesis of a quasi-two-dimensional graphene/molecular sieve composite film material is realized via the interface interaction of graphene sheets with molecular sieve particles. The obtained quasi-two-dimensional graphene/molecular sieve composite film material possesses fully exposed catalytic activity sites and shorter mass transfer pore passages, so that excellent acid catalytic properties are achieved. The preparation method possesses following advantages: the raw materials are widely available; operation technology is simple; operation is convenient to control; repeatability is high; compared with conventional solid acid, the porous graphene/molecular sieve composite film acid catalyst is capable of improving the acidity strength, catalytic performance, and cycling stability of molecular sieve, and industrialized large scale production is convenient to realize. The porous graphene/molecular sieve composite film acid catalyst is high in purity, excellent in structure composition, is of a multistage pore structure, is excellent in mechanical properties, possesses excellent catalytic performance in the field of acid catalysis, can be recycled for a plurality of times, and is promising in application prospect in the field of organic catalytic reaction.