Uniaxial tensile tests of ethylene tetra fluoro ethylene(ETFE) foils are described in this paper.Three kinds of ETFE foils with different thicknesses are used in the tests and the specimens are cut from foils along the machine direction(MD) and the transverse direction(TD).The tensile strength,the tensile strain at break and the stress-strain curve are obtained from the tests.A method to determine the two different turning points of the stress-strain curve is given.According to the curve of stress and strain,the yield stress,the yield strain and the elastic modulus are calculated.By means of high resolution digital photography,the Poisson ratio of ETFE foil is measured.From the test results,it is found that the tensile properties of the foils along the machine direction and the transverse direction are almost the same,which means that the ETFE foils used in the tests can be taken as a type of isotropic material.