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A co-doped LiNb 0.3 Ta 0.7 O 3 :Er 3þ ,Yb 3þ ceramic was prepared by a high temperature solid state procedure. Under the excitation of 980 nm laser radiation, intense 660 nm red light and 550 nm green light emissions corresponding to the 4 F 9/2 ! 4 I 15/2 and 2 H 11/2 / 4 S 3/2 ! 4 I 15/2 transitions of Er 3þ were observed. The change of Yb 3þ concentration has a more significant influence on luminous intensity than the Er 3þ concentration. The emission of red and green lights is attributed to a two-photon process. The upconversion luminescence mechanisms were analyzed in detail.