An optimized micro-torsion tester with high torque resolution designed based on electromagnetism is present. The torque capacity of this tester is 1.3 x 10(-3) N m with resolution of 4 x 10(-8) N m and the angle capacity is 115 deg with resolution of 0.016 deg. In order to verify the reliability of this tester an improved torsion pendulum method is employed with the influences of damping swing and axial force being carefully inspected. The same kind of copper wires with diameter of about 200 Am are tested using both this micro-torsion tester and the improved torsion pendulum. The two kinds of results of shear moduli are very close which verifies the reliability of the self-developed micro-torsion tester. (C) 2017 Elsevier Ltd. All rights reserved.