In this paper, a kind of SMA model based on hysteretic nonlinear theory was developed. Von del Pol nonlinear difference item was introduced to interpret the hysteresis phenomenon of strain-stress curve of SMA. The coupling relationship between strain and temperature was obtained in partial least-square regression method to describe the variation of stiffness with temperature. Based on above, the final relationship among strain, stress and temperature was set up. The result of significance test shows that the final model can describe the characteristics of SMA in different temperature well. The new SMA model broadens the region of temperature, and is easy to be analyzed in theory, which is helpful to application of SMA in engineering fields.