The invention belongs to the technical field of 
investment casting processes, and relates to an 
investment casting process of a complex thin-wall hollow aluminum 
alloy aviation part. The 
investment casting process comprises the following steps that a water-soluble 
ceramic core is manufactured by adopting a 3D printing mode, the water-soluble 
ceramic core is coated with an organic waterproof 
coating, and 
drying is carried out on the water-soluble 
ceramic core; a 
wax injection mold is manufactured according to the shape of a 
casting, a water-soluble ceramic core is placed in the 
wax injection mold, a 
wax material is injected into the wax injection mold after mold closing to form a wax mold, the wax mold is coated with 
gypsum slurry, and after the 
gypsum slurry is hardened, heating dewaxing and 
roasting are carried out to obtain a 
gypsum casting mold; and 
molten metal is poured into the gypsum 
casting mold by adopting a vacuum pouring and pressurizing solidification method to obtain a 
casting mold, and finally the 
casting mold is put into clear water to dissolve and remove the water-soluble ceramic core to obtain the needed complex thin-wall hollow aluminum 
alloy aviation part. According to the investment casting process of the complex thin-wall hollow aluminum 
alloy aviation part, the water-soluble ceramic core and the gypsum 
casting mold are combined, so that the problem that along and narrow inner cavity of the gypsum casting mold sinks is solved, and forming of looseness, cold shut and hot cracks in the casting is reduced through vacuum pouring and pressurizing solidification.