In this paper, a MEMs relay for high power application is investigated. This relay has to hold a current of the order of magnitude of the Ampere and is subject to harsh environment such as high temperature or vibrations which can lead to a premature dysfunction. The paper presents an analytical modelling of the relays considering the geometry, the contact resistance and also the effect of vibrations under which the relay is exposed. A difference of a few percentages is found between the analytical model and the FEM providing interesting optimizing tool.