An automatic four-point bending test method for elastic modulus was presented by means of bengding test on a self-developed small size device.Using a displacement sensor,the method can automatically measure the displacement of the inner support rather than the mild-span of the specimen during loading process.When the devices assembly work was completed,the transducers in instrument were calibrated to fulfil the operating requirements.There is a problem of stiffness shortage due to miniaturization of mechanical structure,so it is very necessary to analyse the frame flexibility of the developed four-point bending instrument with double fixed stay.The frame flexibility coefficient of the instrument was measured to be 3.3 × 10-3 mm/N by means of experimental verification of calibration methods.This paper proposes a four-point bending automatic test method aiming at bulk materials elastic modulus.The elastic modulus of 6061 Al alloy,c11000 Cu alloy were determined just by the bending load-deflection curve in the process of bending tests.The errors of the test results and the standard values of the materials were in the engineering error 5%,which showed the reliability of the test instrument and the feasibility of the testing method.The test method can quickly and accurately determine the elastic modulus of materials under the condition of solid support at both ends.