A synchronous movement-aid device for slide module includes at least one aid device. The aid device includes a first arm, a second arm connected with the first arm and a rotational wheel connected with the second arm and rotatable with the movement of the second arm. The first arm has a pivoted end mounted on a rail. When an external force is applied to the first arm, the pivoted end can freely move along the rail relative to the second arm. The second arm has a fixed end connected to the rotational wheel. When the first arm moves along the rail, the rotational wheel is driven to rotate so as to achieve better synchronous movement effect than the conventional slide mechanism.