The invention discloses an aluminum alloy support assembling device. The device comprises a bottom plate, wherein a positioning unit used for supporting the aluminum alloy support is arranged on the bottom plate, the two sides of the positioning unit are each provided with a guide block, a feeding groove connected with a vibration disc and a discharging groove vertically communicating with the feeding groove are formed in each guide block, outlets of the discharging grooves are formed in the side walls, close to the positioning unit, of the guide blocks, vertical sliding grooves are formed inthe positions, on the two sides of the outlet of the discharging groove, of each guide block, and a movable baffle driven by a baffle lifting air cylinder is arranged in each vertical sliding groove,a pressing rod with the front end facing the outlet is arranged in each discharging groove, the rear end of each pressing rod extends out of the corresponding guide block and is connected with a telescopic air cylinder, and a lifting air cylinder connected with a jacking column is arranged at the position, close to the positioning unit, of the bottom plate. Compared with the prior art, bearings capable of being input into the discharging grooves of the guide blocks through vibration discs are pressed in an aluminum alloy support through the pressing rods driven by the telescopic air cylinders,automatic press-fitting of the bearings is achieved, and the bearing assembling precision and efficiency are improved.