Comprehensive studies on the impact of multiple martensitic transformations B2-B19 on the structure and properties of ultrafine-grained and nanocrystalline titanium-nickel alloys are implemented. It is shown that in coarse-grained, ultrafine-grained and nanocrystalline titanium-nickel alloys consecutive changes in the structure and properties take place, which are induced by phase hardening, when the number of thermocycles increases up to n=100 with quick heating and quick cooling to -196 degrees C. During thermal cycling of coarse-grained and ultrafine-grained Ti50Ni50 alloys via the chosen regimes, the direction of martensitic transformation temperatures changes. First the temperatures reduce, then they increase with the number of thermocycles growing. The transformation temperatures in the ultrafine-grained state of Ti49.15Ni50.85 are more resistant to thermal cycling than in the coarse-grained state. Phase hardening occurs more intensively in ultrafine-grained states of the studied titanium-nickel alloys than in coarse-grained state.