The effect of prestrain on the reverse martensitic transformation of TiNi shape memory alloy fibers embedded in Al matrix has been studied by differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscope (SEM) methods, Results showed that two kinds of reverse transformation occur in TiNi fibers after prestrain. One is the reverse transformation of thermal-induced martensite (TIM), and the other one is that of stress-induced martensite (SIM). The starting temperature of reverse transformation of TIM in the prestrained specimen is almost the same as that in the unprestrained specimen. The starting temperature of SIM increases with increasing prestrain. The fractions of reverse transformed TIM and SIM decrease with increasing prestrain.