The invention provides a manufacturing method of a complicated magnesium alloy component. The manufacturing method comprises the following steps: firstly, a laser quick molding machine is adopted to print a picture, manufactured by UG software, to mold a resin model; then, zirconium sol is brushed on the surface of the obtained resin model, and emery is scattered for curing to obtain a cured emerysand model; the cured emery sand model is put in a sand box, and gypsum pulp is poured to obtain a gypsum model; and finally, a rare earth magnesium alloy is cast in the gypsum model through a vacuumdifference pressure casting machine to obtain a complicated magnesium alloy structural part. Compared with a traditional manufacturing process, the process flow is short, and manufacturing of a metalmold is not needed; compared with sand model casting, a casting is smooth in surface quality and excellent in size precision; a wax mold is manufactured by adopting a 3D printing technology to achieve near-net shaping; a rare earth magnesium alloy casting is prepared by adopting a difference pressure casting process, so that the performance is better; and the manufacturing method is particularlysuitable for trial manufacturing of magnesium alloy parts with complicated structures and small-batch production.