FeTaPt films were prepared by reactive magnetron co-sputtering on Si substrate at 800℃.X-ray difffraction(XRD) measurement revealed that the multilayer films were single phase.The time dependence of magnetization under double-field were measured and studied by Preisach hysteresis model,and we get the parameters through the simulation.The results show that the magnetic intensity linearly changes with the logarithm of time near coercive force.When the external magnetic field deviate away from coercive force,the magnetic viscosity will change its linear variation,which not only related to H1 and H2,but also to the difference value of H1 and H2.The smaller the difference between the H1 and H2,is,the more obvious the nonlinear attenuation is.