The invention discloses a method for preparing a composite sodium negative electrode for a sodium-ion battery and belongs to the field of new energy materials. According to the method disclosed by the invention, metal sodium is deposited in gaps of a three-dimensional carbon material or a foamed porous material and other carriers through a hot infusion melting method or an electrodeposition method, so that the composite sodium negative electrode is prepared, wherein the three-dimensional carbon material is applied to providing a sufficient space for pre-stored sodium in the preparation process and providing a carrier for receiving the metal sodium in the battery cycle process. The composite sodium negative electrode can be widely applied to the sodium-ion battery, a sodium air battery, a sodium-sulfur cell and other sodium metal batteries, is assembled into a sodium-ion symmetric cell to still keep a stable voltage platform under high current density, is capable of inhibiting sodium dendritic growth and stabilizing volume change of the sodium electrode in the battery cycle process, and has the advantages of good cycling stability, long service life and the like. The method disclosed by the invention is rich and cheap in carrier materials, controllable in preparation process, low in production cost and capable of realizing batch production.