A gravity-assisted rotational mechanism and a generator device cooperating therewith. The gravity-assisted rotational mechanism includes multiple concentric rotational members having different sizes and rotatable about the same rotational center, several link members having equal weights for driving the same, and at least one connection member for pivotally connecting the rotational members with the link members. The rotational members can symmetrically push/pull each other. The link members and connection member are respectively mounted on interference sections of at least some of the rotational members to absorb gravitational energy. The energy of the link members is transmitted via the interference sections to the rotational members to form a cycle of energy storage and transmission. The generator device serves to convert the gravitational energy and minimize the rotational inertia loss and increase yield rate of electrical energy.