The invention provides a preparation method of an SnSe/Graphene composite electrode material for a negative electrode of a sodium-ion battery. The method comprises the following steps: with water as a solvent, SnCl<2>.2H<2>O as a raw material and graphene oxide as carbon matrix, preparing an SnO<2>/Graphene composite material by a hydrothermal method in advance; grinding and mixing the SnO<2>/Graphene composite material and selenium powder evenly, putting the mixture into a vacuum tube furnace and carrying out heat preservation at 500-900 DEG C for 0.5-5 hours; and finally obtaining a pure-phase SnSe/Graphene composite material. The particle sizes of SnSe are 5-10nm; and the SnSe grows on the surface of Graphene. The used preparation method is simple, novel and high in repetitive rate; and the adopted vacuum calcination method is clean and free of pollution, and is suitable for the requirements of large-scale production and preparation.