The invention belongs to the technical field of transition metal chalcogenide-carbon materials, and particularly discloses a molybdenum selenide/graphene/carbon nanotube composite material and a preparation method thereof. The method comprises the preparation processes of: quenching a graphene oxide-acidified carbon nanotube aqueous dispersion by liquid nitrogen and carrying out freeze drying to prepare graphene oxide/acidified carbon nanotube aerogel; preparing graphene/carbon nanotube aerogel through a high-temperature carbonization method; and then carrying out in-situ growth of a vertically oriented molybdenum selenide nanosheet on the graphene/carbon nanotube aerogel through a one-step solvothermal method. The prepared graphene/carbon nanotube aerogel has the advantages of stable chemical property, high specific surface area, good conductivity, excellent mechanical property and the like; the molybdenum selenide nanosheet evenly grows on the graphene/carbon nanotube aerogel; a unique three-dimensional porous structure and high specific surface area of the graphene/carbon nanotube aerogel are fully utilized; and the composite material disclosed by the invention can be taken as an ideal high-performance electrocatalytic material and an electrode material for new energy devices of a lithium-ion battery, a solar battery and the like.