By solid-state synthesis method, Er3+/Yb3+ co-doped Al2O3 phosphors were prepared. The X-ray diffraction (XRD) and luminescence spectra of the samples were measured. Under 975nm excitation, the up- and down-conversion emissions of the samples un-doped and doped with Zr4+ ion were studied. The intensities of up-conversion red emission and near infrared fluorescence in the sample doped with Zr4+ ion are stronger than those in the sample un-doped with Zr4+ ion. The full width at half-maximum of the near infrared fluorescence in the Zr4+ ion doped sample is 159nm. The results show that the luminescent characters of the Er3+/Yb3+ co-doped Al2O3 phosphors are relaxed to the Zr4+ ion concentration. Our materials are helpful in developing Er3+ amplifier.