The invention provides a preparation method for a NaY molecular sieve. The method comprises the main steps: according to the proportioning requirement of a molecular-sieve directing agent to uniformly mix a silicon source, an aluminium source and an alkaline solution, stirring at 15 DEG C-60 DEG C for 0.5-48 h for ageing, so as to prepare the directing agent; according to the proportioning requirement of the molecular sieve to add a solid silicon source into an alkaline solution at 20 DEG C-80 DEG C under the stirring condition, stirring for 0.5-5 h, then adding the above directing agent and stirring for 1-5 h, then adding an aluminium source and mixing uniformly, so as to prepare a gel reaction mixture; and performing crystallization on the above gel reaction mixture at 80-140 DEG C for 10-40 h, and then performing filtering, washing and drying, so as to prepare the NaY molecular sieve. The method improves the single-kettle yield from current about 10% to about 20% under the premise of not changing conventional equipment for industrial production of the NaY molecular sieve, and the prepared NaY molecular sieve has high crystallization degree and high silica-alumina ratio.