To better utilize the electrical resistance of shape memory alloy(SMA) for health monitoring and designing SMA sensor,a model of electrical resistance properties of NiTi SMA is developed.The relationship between the relative variation of electrical resistance and the strain of NiTi SMA with different phases is analyzed under different temperatures by using this model.And the corresponding experiments have been conducted on NiTi SMA wires,through which the validity of this model is verified.When NiTi SMA is employed as a sensing element,the transformation temperatures of NiTi SMA should be determined under application conditions.