The invention provides an aluminum alloy pressure casting blank precise forming process method. The method comprises the following steps that (1), a mould is fabricated according to the structure of acasting; (2), a wax mould, a pouring cup, a horizontal pouring channel, a straight pouring channel and an inner pouring gate are pressed through a wax injector, the wax mould is subjected to shape trimming, the wax mould is subjected to mould combination according to a combination diagram, and then the combined wax mould is subjected to oil removal; (3), the wax mould subjected to mould combination is subjected to multi-layer san suspension; (4), dewaxing is performed, a mould shell obtained after dewaxing is dried by 20 hours or more in the ventilation condition, the mould shell is subjectedto calcination in a chamber type electric resistance furnace, and the mould shell is inspected after the mould shell is cooled to the room temperature; (5), the washed mould shell is required to be subjected to a shell drying process; (6), sodium silicate-bonded sand is adopted for modelling, and then the sand mould is subjected to drying treatment; (7), a molten aluminum alloy is smelted, pressure-regulating pouring is adopted, when half of the crystallization period is reached, the temperature of the sand mould is lowered by 5-10 s, and the temperature of the sand mould is decreased by 2-4DEG C; (8), the casting is cleaned; (9), the casting is subjected to heat treatment.