The invention discloses a preparation method of a carbon-based composite iron cyanamide material, which comprises the following steps: firstly, respectively taking ferramine oxalate, urea and conductive carbon according to a mass ratio of 1:2:(0.1-1), fully grinding and mixing to obtain uniform mixture powder, and marking the product as A; adding a surfactant into the product A, dissolving in water, dispersing, and freeze-drying to obtain a black product marked as B; and pyrolyzing the product B in a protective atmosphere to obtain a product C, namely the carbon-based composite iron cyanamidematerial. The obtained carbon-based composite iron cyanamide material is taken as a negative electrode material of the sodium ion battery. According to the invention, FeCN2 and conductive carbon are compounded by adopting a high-temperature pyrolysis and nitridation method; the synthetic product carbon-coated iron cyanamide active material is used as a negative electrode material of a sodium ion battery, a new material system is constructed by adding a conductive carbon material, the conductivity of the material is enhanced, and the preparation method is simple to operate, low in cost, safe and non-toxic, and is expected to realize industrial production.