Bundle conductor is commonly used in UHV transmission lines. In order to clearly reveal the influences of anti-galloping fittings on torsional stiffness properties, such as the rotary clamp spacers and heavy spacer, their values for bundled LGJ-500/45 wires under various working conditions are determined by test, through which the effect law of anti-galloping fittings’ types, installation modes and quantity on bundled wire torsional stiffness is analyzed. The results show that keeping the test span constant, the more anti-galloping fittings just like spacers are used in single span, the smaller torsional stiffness becomes; there are little differences between torsional stiffness values of bundle conductor systems with rotary clamp spacers or heavy spacer; their nonlinear characteristics should not be ignored. This work is supported by Science and Technology Project of State Grid Corporation of of China (No. GC71-17-024).