Abstract: Thermodynamic hysteresis model has received much attention benefited from its ability to reflect magnetic characteristics of materials physically. Aimed for acquiring higher simulated accuracy at unsaturated region, this paper proposed an improved thermodynamic hysteresis model based on the principle of pinning sites distribution. The proposed model could satisfy solution accuracy at a wide range of induction by only introducing a limited number of pinning sites, which are contributed from lattice defects produced by the manufactured process of magnetic material. At the beginning, the formation of hysteresis phenomenon was analogized to mechanical device, which provides a better understanding about the relationship of imposed field intensity and reversible field intensity. Then, the pinning sites distribution density at different peak field intensity could be deduced by analyzing variation tendency between coercivity and imposed field intensity. Based on presumed number of pinning sites, different pinning sites strength and their weight were acquired according to pinning sites density and imposed field intensity. Furthermore, reversible field intensity was obtained, which is the input variable of proposed model. The improved thermodynamic model and original thermodynamic model were compared to measurement respectively, and results proved the efficiency of the proposed one.