A dual-wavelength laser flash Raman spectroscopy method for thermophysical characterization of a 2D nanomaterial, comprising: acquiring temperature rise data of a sample comprising the 2D nanomaterial by heating the sample with a heating pulse from a heating pulsed laser and then generating Raman scattering in the sample with a probing pulse from a detecting pulsed laser, the heating pulse having a wavelength different from a wavelength of the probing pulse, and the heating pulse and the probing pulse having the same pulse period; and determining a thermophysical parameter of the sample based on the temperature rise data, wherein step further comprises: heating, during a first pulse duration t h, the sample with the heating pulse from the heating pulsed laser to enable the sample to reach a steady temperature T 2 from an ambient temperature T 1 which is controlled by a temperature control platform connected to a sample holder of a sample chamber for the sample; then cooling the sample from the steady temperature T 2 to the ambient temperature T 1 during a first time interval t c, and detecting a Raman signal of the sample by generating Raman scattering in the sample with the probing pulse from the detecting pulsed laser, the probing pulse starting at a time delay t d after the end of the first pulse duration t h and during a second pulse duration t p within the first time interval t c, to acquire a Raman spectrum of the sample from the detected Raman signal; and determining, based on a linear relationship between a Raman spectrum peak shift and a temperature rise, a temperature rise T 3 of the sample during the second pulse duration t p based on a shift value of a characteristic peak of the 2D nanomaterial in the Raman spectrum acquired in step. acquiring temperature rise data of a sample comprising the 2D nanomaterial by heating the sample with a heating pulse from a heating pulsed laser and then generating Raman scattering in the sample with a probing pulse from a detecting pulsed laser, the heating pulse having a wavelength different from a wavelength of the probing pulse, and the heating pulse and the probing pulse having the same pulse period; and determining a thermophysical parameter of the sample based on the temperature rise data, heating, during a first pulse duration t h, the sample with the heating pulse from the heating pulsed laser to enable the sample to reach a steady temperature T 2 from an ambient temperature T 1 which is controlled by a temperature control platform connected to a sample holder of a sample chamber for the sample; then cooling the sample from the steady temperature T 2 to the ambient temperature T 1 during a first time interval t c, and detecting a Raman signal of the sample by generating Raman scattering in the sample with the probing pulse from the detecting pulsed laser, the probing pulse starting at a time delay t d after the end of the first pulse duration t h and during a second pulse duration t p within the first time interval t c, to acquire a Raman spectrum of the sample from the detected Raman signal; and determining, based on a linear relationship between a Raman spectrum peak shift and a temperature rise, a temperature rise T 3 of the sample during the second pulse duration t p based on a shift value of a characteristic peak of the 2D nanomaterial in the Raman spectrum acquired in step.