The paper aims to study the constitutive relation of Metal Rubber and establish a modified Mooney-Rivlin model of Metal Rubber which is suitable for engineering calculation and numerical simulation. Based on the characteristics of nonlinear stiffness and compressibility in the deformation process of Metal Rubber, the deformation of Metal Rubber specimen was divided into two parts including Isochoric part and Volumetric part . The effects of loading speed, solid volume fraction and wire diameter on the Volumetric part of Metal Rubber deformation were studied by orthogonal test. The influence order of experimental factors on the modified Mooney-Rivlin model is Solid volume fraction > Wire diameter > Loading speed. And the influence of loading speed on the deviation is much less than the solid volume fraction or wire diameter. The modified Mooney-Rivlin model has a better fitting effect and can better reflect the nonlinear stiffness characteristics of Metal Rubber, which provides a theoretical reference for the practical application of Metal Rubber.