The present invention provides a Ga-based van der Waals room-temperature ferromagnetic crystal material, preparation and use thereof, which belong to the technical field of nano magnetic material preparation. The materials include Fe3-aGabTe2 (a=−0.3 to 0.1, b=0.8 to 1.2) and Fe5-c GeGadTe2 (c=−0.2 to 0.2, d=0.01 to 0.5). The growth method of Fe3-aGabTe2 (a=−0.3 to 0.1, b=0.8 to 1.2) is a self-flux method, using excess Ga and Te as flux to grow crystals. The growth method of Fe5-c GeGadTe2 (c=−0.2 to 0.2, d=0.01 to 0.5) uses iodine as a transport agent to grow crystals. The Ga-based van der Waals room-temperature ferromagnetic crystal Fe3-a GabTe2 (a=−0.3 to 0.1, b=0.8 to 1.2) and Fe5-cGeGadTe2 (c=−0.2 to 0.2, d=0.01 to 0.5) materials have Curie temperature of 330 K to 367 K and 320 K to 345 K, and the saturation magnetic moments are 50 emu/g to 57.2 emu/g and 80 emu/g to 88.5 emu/g, respectively.