The invention discloses a carrier, and a preparation method and an application thereof. The carrier comprises a dealuminated Y-type molecular sieve and heat-resistant inorganic oxide, wherein the dealuminated Y-type molecular sieve has a lattice constant of 2.430 to 2.450 nanometers, a relative crystallinity of 65% or above and a secondary pore volume of 0.1 to 0.3 mL/g; and in terms of oxide, the content of an alkali metal element is 0.2 wt% or below, and the number of non-framework aluminum in a unit cell is 3 or below. The invention also discloses a catalyst adopting the carrier and an application thereof. The invention further discloses a hydrocracking method adopting the catalyst. The molecular sieve in the carrier has high crystallinity, abundant secondary pores, and lower non-framework aluminum content. The catalyst prepared from the carrier shows better catalytic performance in a hydrocracking reaction of hydrocarbon oil, and can achieve a good balance among catalytic activity, middle distillate selectivity and tail oil BMCI value.