The proposed paper presents the fabrication and the modeling of magnetic membranes composed of Fe2O3 or NdFeB powder, and which could be polarized in order to create soft magnets. In this paper, two hyperelastic models (Yeoh and Gent) are chosen to describe the mechanical behaviour of such membrane. For different ratio mass of powder and several thicknesses of membranes, a tensile test is achieved in order to evaluate the parameters of each model. This step allows fitting models curves with measurement curve and evaluate the relative error between each model and measurement. Thus, the best model can be determinate. An implementation of these parameters into FEM software allows computing the displacement of the membrane in function of the applied pressure. A simple setup constituted of the air chamber, the laser and the membrane support leads to a measure of the membrane displacement in the real case. The low relative error of 20% validates the proposed approach.