Provided is a method for preparing a Y type molecular sieve having a high silica-to-alumina ratio, comprising: mixing deionized water, a silicon source, an aluminum source, an alkali source, and a tetraalkylammoniumcation source as a template agent to obtain an initial gel mixture; after aging the initial gel mixture at an appropriate temperature, feeding the gel mixture into a high pressure synthesis kettle for crystallization; separating a solid product, and drying to obtain the Y type molecular sieve having a high silica-to-alumina ratio. The method provides a phase-pure Y type molecular sieve having a high crystallinity, the SiO2/Al2O3 thereof being not less than 6.