Er 3+ -doped Y 2 Ti 2 O 7 nanocrystals were fabricated by the sol–gel method. While the annealing temperature exceeds 757°C, amorphous pyrochlore phase Er x Y 2−x Ti 2 O 7 transfers to well-crystallized nanocrystals, and the average crystal size increases from ∼70 to ∼180nm under 800–1000°C/1h annealing. Er x Y 2−x Ti 2 O 7 nanocrystals absorbing 980nm photons can produce the upconversion (526, 547, and 660nm; 2 H 11/2 → 4 I 15/2 , 4 S 3/2 → 4 I 15/2 , and 4 F 9/2 → 4 I 15/2 , respectively) and Stokes (1528nm; 4 I 13/2 → 4 I 15/2 ) photoluminescence (PL). The infrared PL decay curve is single-exponential for Er 3+ (5mol%)-doped Y 2 Ti 2 O 7 nanocrystals but slightly nonexponential for Er 3+ (10mol%)-doped Y 2 Ti 2 O 7 nanocrystals. For 5 and 10mol% doping concentrations, the mechanism of up-converted green light is the two-photon excited-state absorption. Much stronger intensity of red light relative to green light was observed for the sample with 10mol% dopant. This phenomenon can be attributed to the reduced distance between Er 3+ –Er 3+ ions, resulting in the enhancement of the energy-transfer upconversion and cross-relaxation mechanisms.