In this study, the Ti-60Ta alloy bars were prepared by vacuum arc smelting and then forging process. The bulk samples of Ti-60Ta alloy were cut from the bars, some of them were quenched in the water. The spherical powder of Ti-60Ta alloy were prepared by PREP (plasma rotating electrode process). The microstructure and phase transition process were characterized by SEM, XRD, TEM, DSC and so on. It revealed that both of the bulk samples and powders were mainly composed of β-Ti with bcc structure. With the powder size decreasing, the cooling rate was increased during the rapid solidification process, the content of α" martensite phase increased, while the content of β-Ti decreased gradually. The bulk samples were kept at 1000℃ for 60min then quenched in the water, resulting in a small amount of α" martensite phase. The results of TEM and SEAD revealed the lath α" martensite phase with a width of 50 nanometers formed in the powders after rapid solidification, the α" martensite phase mainly precipitated at grain boundaries.