The invention provides a method for preparing a dense super-large negative thermal expansion bulk material. The method comprises the steps: firstly, preparing precursor powders of Mn4N, Mn3ZnN and Mn3SnN, mixing Mn4N, Mn3ZnN and Mn3SnN, and pressing to be a wafer; then, preparing a negative thermal expansion material by high-temperature sintering: sealing the wafer in a vacuum quartz glass tube and sintering to obtain Mn3(MnxZnySnz)N; and pulverizing the Mn3(MnxZnySnz)N into powder, placing the powder into a graphite mold, sintering the powder in a discharge plasma furnace, cooling and takingout. The method can prepare a dense negative expansion bulk material Mn3(MnxZnySnz)N, and has the advantages of simple preparation process, strong operability, high material density, and high absolutevalue of negative thermal expansion coefficient up to 100 ppm/K.