The actuating performance and electro-magnetic and mechanical coupling characteristics of an electromagnetic inertia actuator, which is commonly used in an active vibration reduction system, is investigated in this paper. Firstly, a multi-physics field coupling model of the actuator"s mechanical-electrical-magnetic system is established and verified through experimental tests. Then the relationship between the structural dynamics parameters, electromagnetic parameters, and actuating performance of the electromagnetic inertia actuator is explored, revealing the internal dynamics laws and mechanical-electrical-magnetic coupling characteristics of it. Finally, the factors affecting the output force of the actuator in the active vibration reduction system are discussed, and the limitation on the maximum output force is obtained. The possibility of improving the low-frequency output characteristics of an electromagnetic inertia actuator is explored, providing a basis for the design and optimization of it.