Physical properties of the two-step complete thermoelastic Ni53.2Mn22.6Ga24.2 single crystal are investigated by various measuring methods, especially, the stress-strain characteristic at different temperatures is studied. The results show that at low deformation temperatures the pressing stress along the ［001］ direction of the parent phase would induce a two-step martensitic transformation, and the alloy exhibits pseudoelastic characteristics. But at relatively high temperatures, the alloy exhibits complete superelastic characteristics, and only one-step martensitic transformation is observed. Furthermore, the dependence of critical stress on the deformation temperature for the martensitic transformation and intermartensitic transformation is calculated by the thermodynamic theory, and the result is consistent with that of two-step martensitic transformation obtained by experiment.