Disclosed in the present invention is an application of a metal sulfide piezoelectric material in piezoelectric catalytic reduction of CO2. The internal electric field generated by the piezoelectric material under external mechanical stimulation pushes electrons and holes to migrate in opposite directions, so that natural advantages are provided for separation and transmission of electron-hole pairs, but there is no report in the prior art that CO2 is reduced into C2+ products by means of piezoelectric catalysis. The present invention provides a metal sulfide piezoelectric nanomaterial and a preparation method therefor. The metal sulfide piezoelectric nanomaterial is used for piezoelectric catalytic reduction of CO2 for the first time, especially piezoelectric catalytic reduction of CO2 to obtain C2+ products so as to broaden the technical route of catalytic reduction of CO2.