The invention discloses a preparation method of a sandwich-structure carbon-base composite material. The preparation method comprises the following steps: (1) uniformly mixing chitosan and a zinc saltpore-forming agent, and carrying out carbonization treatment, so as to obtain a porous carbon nanosheet; and (2) soaking the porous carbon nanosheet obtained in the step (1) into a soluble nickel salt solution, taking out, drying, and carrying out CVD vapor deposition, so as to obtain the sandwich-structure carbon-base composite material. The preparation method has the beneficial effects that theraw materials are easily available, the repeatability is good, and the industrial production is easily realized. The invention discloses the sandwich-structure carbon-base composite material with good electrical conductivity. The invention further discloses application of the sandwich-structure carbon-base composite material as a negative electrode material in sodium-ion batteries. A sodium-ion battery produced from the carbon-base composite material prepared by virtue of the preparation method is high in specific capacity and good in rate capability and cycle performance.