In this paper, a novel method Micro-fields activated sintering technology was applied to the preparation of NiTi alloy. Cylindrical specimens with the diameter of 4mm and a height of 4mm were prepared successfully in a short time (about 8mins). The effect of heating rate on the preparation of NiTi alloy was discussed. The research result shows that the axial reduction in rapid heating stage was the biggest among the four sintering stages of Micro-FAST, which directly influenced the quality of sintering samples. In the experimental range of 25℃/s to 125℃/s, the relative densities of NiTi alloy sintered by Micro-FAST was decreased with the increasing heating rates. The higher the heating rate, the bigger the electric current is. Under electric current, atomic diffusion was promoted. As a result, NiTi2 and Ni3Ti were easier to be formed, and the effect of Kirkendall was aggravated. Meanwhile, local liquid-phase was produced by local high temperature under electric current, which promoted the fusions of particles and pores.