The samples of La0.80Sr0.15Ag0.05 Mn O3/x(Cu O)(x = 0, 0.05, 0.10, 0.15, 0.20) were prepared by the solid-state reaction method, and the structure of the samples was detected by X-ray diffraction(XRD), scanning electron microscope(SEM) equipped with energy dispersive spectroscopy(EDS), electric transport mechanism, and magnetoresistance enhancement, and the temperature stability of magnetoresistance of the samples was studied through resistivity–temperature(q-T) curves, q-T fitted curves, and magnetoresistance–temperature(MR-T) curves.The results indicate that q-T data can be fitted by the formula q = q0 AT2 very well, and the electric transport mechanism of all the samples in metal-like area is the scattering of single magneton upon spin electron; the magnetoresistance of composite samples is far larger than that of the original material, and the MR peak value of the sample with x = 0.20 is nearly 4 times as large as that of the sample with x = 0; composite samples have comparatively good temperature stability of magnetoresistance in the temperature range of 200–260 K, and the magnetoresistance of the sample with x = 0.15 almost does not change with temperature and keeps at(5.03 ± 0.20) % in the temperature range of 210–260 K.
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