Abstract: The aging treatment processes for Ti-50.8Ni-0.1Nb shape memory alloy were carried out at 400 ℃for 1-50 h.The effect of aging time on the microstructure, phase transformation, shape memory behavior and tensile property of the alloy was investigated by the transmission electron microscope, differential scanning calorimetry and tensile test. The results show that with the increase of the aging time from 1 h to 50 h, the Ti₃Ni₄ precipitates in Ti-50.8Ni-0.1Nb alloy aged at 400 ℃grow from small particle to large sheet, the transformation types of the alloy change from B2→R→B19'/B19'→R→B2 to B2→R→B19'/B19'→B2 (B2-parent phase, CsCl type; R-R phase, rhombohedral; B19'-martensite, monoclinic) during cooling/heating, the R phase transformation temperature increases from31.3 ℃ to 46.8 ℃, the martensitic transformation temperature increases from-127.5 ℃ to -10.3 ℃, the temperature hysteresis of martensitic transformation decreases from 131.7 ℃ to 57.2 ℃, the temperature hysteresis of R phase transformation changes in the range of 3.8-5.0 ℃.The tensile strength of the alloy aged at 400 ℃ for 5-50 h is higher, and it changes in the range of 1360-1385 MPa; the elongation of the alloy aged at 400 ℃ for 1-10 h is larger, and it changes in the range of 15%-17%.The alloy aged at 400 ℃ for 1 h exhibits superelasticity, and the alloy aged at 400 ℃ for 5-50 h exhibits shape memory effect.