A micro-scale uniaxial tension test method for measuring material mechanical properties of thin film materials is introduced in this paper. A self-developed test device is established based on the CMT8202 tension test machine. The Interference Strain/Displacement Gauge (ISDG) method is used to measure the strain in the micro-samples. The three dimensional finite element method (FEM) is utilized to optimize specimen geometry configuration and to reduce the stress concentration in specimen around grip region. The experiments are carried out for the polycrystalline copper thin film. The results show that stress-strain curves and the Young’s modulus of the thin film material can be obtained by micro-scale tension test. The Young’s modulus determined by micro-sample for polycrystalline copper thin film has a good agreement with published results.