Abstract: The (Y_0.98-xYb_xEr_0.02)₂Ti₂O₇ (x=0, 0.02, 0.04...0.10) phosphor powders were synthesized by the Sol-gel method. The crystal structure and upconversion emission luminescence properties were investigated by XRD and luminescence spectroscopy. The effects of Yb³⁺ concentration on the upconversion emission luminescence properties and the mechanism of upconversion emission were studied. The results showed that the structure of samples belonged to pyrochlore phase with FCC structure. Excited by 980nm, the samples exhibited strong upconversion emission luminescence and the color of emission luminescence can be tuned by the Yb³⁺ concentration. The upconversion green and red emission luminescences of samples were two-photo process. The cross-relaxation process was dominant for the upconversion red emission luminescence of samples.