Vacuum-assisted local supplement pressure technology was used to produce back wheel hub of magnesium alloy motorcycles. The mould was poured tangentially via the rim edges of the wheel with collected-residual alloy at center

effectively eliminating the inclusion and shrinkage hole （porosity） in hot spot in the wheel. Design of vacuum system and vacuum process could prevent oxidation and air entrapment

and the vacuum degree in the mould cavity could reach 2.9kPa. Local supplement pressure could avoid the formation of shrinkage hole resulted from different solidification rate from center of wheel hub to their edge. Meanwhile

some defects easily occurred in magnesium alloy production

such as cold shut

shrinkage hole

crack

inclusion

and deformation

were analyzed

and countermeasures were presented. Practical production verified that vacuum-assisted local supplement pressure could obtain desirable magnesium alloy wheel.