The invention provides a g-C3N4/NiCo2S4 composite material, a preparation method and application thereof. The material is obtained by mixing g-C3N4 and NiCo2S4 in a solid phase manner or a liquid phase manner. According to the invention, stability of the material is greatly improved; and a composite electrode is used as a working electrode material of a super capacitor for testing, so quite high specific capacitance, quite good rate performance and circulation stability are achieved under a condition of the big current density.