Metal rubber is a kind of non-linear and nonelastic material that has excellent damping performance.It can especially be compatibly used in aviation,space flight and atrocious environment.Some experimental studies of stiffness performance of thinner MR material have been carried out in this paper.The factors that affect the performance of MR and their affecting rules have been summed up on the basis of plentiful tests.There is important and practical value for perfecting the MR.The investigation results provided credible evidence for the application and theoretical research of MR damper or material.The strain-stress relation of MR is established and the coefficients of the equation are given based on the test data.The result of the theoretic calculation is consistent with the experimental data.