The invention discloses application of an electrochemical sensor constructed by a CoS2/nitrogen-doped graphene composite material in glucose electrochemical analysis and belongs to the technical fields of inorganic material synthesis and application. The composite material is prepared by the following steps: adding hydrazine hydrate into graphene oxide in an alkaline environment to convert graphene oxide into nitrogen-doped graphene; adding cobalt nitrate and L-cysteine, and performing a hydrothermal reaction. The preparation method is simple, and is small in reagent dosage and low in energy consumption; the reaction is carried out in an aqueous phase and is environmentally friendly; and the reaction conditions are mild, and the product is convenient to separate and purify. According to the composite material disclosed by the invention, nitrogen-doped graphene with the advantages of large specific surface area, high heat stability, high electrical conductivity and high biocompatibility is taken as a substrate material, a CoS2 nanometer material with high electron transfer rate is loaded, a modifier with an excellent catalytic effect in an electrochemical redox reaction of glucose is prepared, and the electrochemical sensor constructed with the modifier can be used for detecting trace glucose with high sensitivity and high selectivity.