The invention belongs to the technical field of catalyst preparation, and particularly relates to a mesoporous and microporous MFI type nano molecular sieve with flaky pastry-shaped morphology and a preparation method and application thereof. The specific synthesis method is as follows: silicon source, aluminium source, mesoporous template, microporous template and water are mixed according to a proportion, the mixture is put into a reaction kettle and crystallized, the crystallized product is washed, dried and roasted and undergoes ion exchange, and thereby the mesoporous and microporous MFItype nano molecular sieve is obtained. The invention adopts Bola type tetra-head-group quaternary ammonium surfactant as the mesoporous template and tetrapropylammonium hydroxide as the microporous template, the guiding microporous structure can be assumed as a column, preventing the structural collapse of the roasted molecular sieve, consequently, the structural stability of the molecular sieve is remarkably enhanced, and the degree of crystallinity is high; the introduction of mesopores shortens the delivery path of micropores within unit volume, and decreases the mass transfer resistance ofmacromolecular catalytic reaction; and moreover, when applied in alkylation reaction (such as the heterogeneous reaction between sym-trimethylbenzene and phenylcarbinol), the mesoporous and microporous MFI type nanoscale molecular sieve has a good catalytic effect.