A making method of a low-residual voltage piezoresistor of low-resistivity ZnO crystal grains is characterized in that raw materials for making the low-residual voltage piezoresistor include zinc oxide (ZnO), bismuth oxide (Bi2O3), diantimony trioxide (Sb2O3), manganese dioxide (MnO2), chromium oxide (Cr2O3), cobalt sesquioxide (Co2O3), silica (SiO2), aluminum nitrate crystals (Al(NO3)3.9H2O) and gallium nitrate (Ga(NO3)3.9H2O); and the making method comprises the steps of crude seed crystal preparation, primary sintering, seed crystal refinement, raw material and secondary sintering. The method has the following advantages: the structure components and the structure change of the above material in the preparation method can be artificially controlled through strictly changing the sintering process flow and controlling process parameters, so the resistivity of the grains is reduced, the residual voltage of the ZnO piezoresistor is reduced, and increase of the leakage current and decrease of a nonlinear coefficient are inhibited, thereby the material has high performances and is suitable for industrial applications.