Based on the lubricating and unsteady properties of rolling processes and hydrodynamic analysis, a film distribution model of the deformation zone which concerns the steady and unsteady conditions is set up and the film wave coefficient is proposed which is used to study the absolute fluctuation of unsteady film thickness. The von Karman equation is used to describe the stress distri-bution of rolling interfaces under the steady and unsteady conditions. According to the stress distribution under the steady condition, the stress wave coefficient is proposed which is used to study and describe the absolute fluctuation of unsteady stress. It is found that large reduction results in a thinner film thickness and a larger hydrodynamic pressure and shear stress in the deformation zone under the steady condition. Under the unsteady condition, as the fluctuation of disturbance factors such as inlet strip thickness intensifies, the film wave coefficient increases, indicating that the absolute fluctuation of film thickness gets larger. The position and value of the pres-sure stress peak change with time under the unsteady condition. The absolute fluctuation of unsteady film thickness has a greater impact on the hydrodynamic pressure than on the shear stress. When the absolute fluctuation of film thickness is 6.33%, the pressure stress and the shear stress have a 1.17% and a 0.24% absolute fluctuation, respectively.%针对轧制过程非稳态及润滑特性，通过流体力学分析，建立稳态、非稳态轧制变形区油膜厚度分布模型，提出油膜波动系数以研究油膜厚度的绝对波动，应用卡尔曼微分方程分析了稳态、非稳态轧制界面应力分布，并以稳态应力分布为基础提出应力波动系数以研究变形区应力的绝对波动.结果表明：稳态下压下率增加，轧制界面油膜变薄，压应力、切应力均增加；非稳态下随着入口板带厚度等扰动因素的波动加剧，油膜波动系数变大，绝对波动加剧；不同时刻非稳态压应力波峰的位置和数值都会发生变化；相比于切应力，油膜波动对压应力的影响比较大，当油膜厚度发生6.33%的绝对波动时，压应力和切应力分别产生1.17%和0.24%的绝对波动.
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