LaNbO₄:Tm³⁺,Yb³⁺ phosphors were synthesized by a solid state method.Their structure and fluorescence properties were characterized by X-ray diffraction and fluorescence spectra.The results shown that the dopants did not affect the structure of LaNbO₄ matrix and all samples crystallized in monoclinic structure.Red and blue emition from Tm³⁺ were observed that excited by 980nm laser because of the energy transfer from Yb³⁺ to Tm³⁺.The effect of doping concentration was discussed,and the optimal doping concentration was obtained to be 0.1mol% and 15mol% repectively.Upconversion luminescence mechanism was discussed using the relation between the emission intensity and upconversion power of the 980nm laser.The pump-power dependence of UC emission intensity suggested the two-photon and three-photon absorption processes involved in the UC mechanism.Finally,its temperature sensing peoperties were studied based on the relative intensity ratio of the two upconversion emission bands.As a result,it was confirmed that LaNbO₄:Tm³⁺,Yb³⁺ had potential application in the non-contact optical temperature sensors.