Er3+ doped potassium gadolinium molybdate (KGM) phosphor with sensitizer Yb3+ ion was synthesized by the Pechini method using citric acid and ethylene glycol.The crystallization processes of the phosphor precursors were characterized by X-ray diffraction (XRD) and thermogravimetry-differential scanning calorimetry (TG-DSC),which indicated that ultrafine uniform crystallites of KGM∶Er,Yb were obtained by sintering the precursors at above 650 ℃ for 5 h.Upconversion luminescence (UL) spectra of the samples were studied by a 976 nm semiconductor laser diode (LD) excitation.The UL spectra exhibited the green and red emission bands that were attributed to the 2H11/2,4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+,respectively.The possible UL mechanisms of Er3+ were explained by means of an energy level diagram.The maximum luminescent intensity was achieved when the concentration of Er3+,Yb3+ arriVed at 1 mol.％ and 20 mol.％,respectively.