The invention discloses an aluminum alloy preparation device. When the device is used, firstly, TiH2 powder, aluminum powder and borohydride titanium powder are mixed to be uniform, and the mixture ispressed into a second alloy precast block; and boron powder, titanium powder and aluminum powder are pressed into a first alloy precast block, the two blocks are put or pressed together, after the first alloy precast block is ignited, the second alloy precast block is heated, the TiH2 powder and the borohydride titanium powder powder are decomposed and further subjected to a self-propagating reaction, finally, fine TiB2 particles, melt containing hydrogen, titanium and aluminum and hydrogen are formed in the second alloy precast block through the self-propagating reaction, high pressure is generated at the hydrogen forming moment, the TiB2 particles and liquid drops of the melt containing hydrogen, titanium and aluminum are sprayed into pre-smelted pure aluminum melt, and after degassingand deslagging are completed, a Al-5%Ti-xB intermediate alloy is formed. By means of the device, the sizes of the TiB2 particles can be reduced, the dispersion effect of the TiB2 particles in the intermediate alloy is improved, meanwhile, environmental pollution caused by preparation of a refiner is reduced, and then the mechanical performance of the prepared aluminum alloy is improved.