Abstract: Three as-cast high Ni-rich NiTi alloys（59wt% Ni-61wt% Ni） were annealed for 5 h within 400 ℃-950 ℃,and the effects of annealing temperature on the microstructure evolution and martensitic transformation of the as-cast Ni-rich NiTi alloys and their relationship with hardness were studied. The results show that the hardness of as-cast high Ni-rich NiTi alloy decreases with the increase of Ni content. Annealing above 700 ℃ can further improve the hardness of as-cast high Ni-rich NiTi alloy. After annealing at 950 ℃, the hardness of the 59NiTi, 60NiTi and 61NiTi alloys increases to 81.6 HRA,87.3 HRA and 86.3 HRA, respectively. The high hardness of the as-cast 59NiTi alloy comes from the uniformly distributed Ni₄Ti₃phase in the alloy. The coarse Ni₃Ti₂phase and Ni₃Ti phase are the reasons for the decrease of the hardness of the60NiTi and 61NiTi alloys. With the increase of the annealing temperature, the coarse second phases are dissolved in the matrix, which can reduce the M_sof the NiTi alloy and further improve the hardness.