The invention relates to a 
fluoride-doped high-capacity Gd-Mg-Ni-based composite 
hydrogen storage material and a preparation method thereof. The 
fluoride-doped high-capacity Gd-Mg-Ni-based composite 
hydrogen storage material comprises the following components: GdxMg100-x-yNiy + m wt.% (TiF3, NbF5), x and y are atomic ratios, x is more than or equal to 1 and less than or equal to 9, y is more than or equal to 5 and less than or equal to 20, m is the weight percentage of the TiF3 or the NbF5 in an 
alloy, and m is more than or equal to 2 and less than or equal to 8. Preferably, x is equal to 5, y is equal to 10, and m is equal to 5, namely Gd5Mg85Ni10 + 5wt.% (TiF3, NbF5). According to the preparation method, the preparation method comprises the following steps that medium-frequency 
induction heating smelting is adopted under the protection of high-purity 
helium, 
liquid alloy is injected into a 
casting mold, and a cylindrical matrix 
alloy cast 
ingot is obtained; and an as-cast 
alloy is crushed mechanically and sieved with a 200-mesh 
sieve, sieved alloy 
powder and a certain amount of catalysts (TiF3 and NbF5) are filled into a stainless 
steel ball milling tank, vacuumizing is achieved, high-purity 
argon is filled, and ball milling in a planetary high-energy 
ball mill is carried out for a certain time to obtain the alloy 
powder with ultrafine grains (nanoscale). According to the 
fluoride-doped high-capacity Gd-Mg-Ni-based composite 
hydrogen storage material and the preparation method thereof, through component design, 
microstructure regulation and control and addition of a multi-element catalyst, the 
thermal stability of alloy 
hydride is reduced, and the 
hydrogen absorption and 
desorption thermodynamic and dynamic performance of the alloy is improved.