Abstract: Phase transition temperatures are the key parameters that decide the processing and operating temperatures. In this paper, Transformation of Ni-Ti shape memory alloy fiber was investigated by electrical resistance method. The relationship between the resistivity and temperature was derived by logistic’s martensite volume growth model and mixing rule. A signal acquisition system is established to measure the resistance and temperature of the Ni-Ti fiber. By the derivation of resistance-temperature curves, the measured phase transition temperatures of the Ni% 55.5a.t.% fiber sample are Ms = 34.4 ℃, Mf = 25.6 ℃, As = 39.4 ℃and Af = 51.1℃, respectively. Compare with the DSC testing method, the electrical resistance method is more accurate, thus can detect the fiber phase transformation more effectively.