To increase the retaining force, a novel design for a concentric, bi-directional, electromagnetic valve actuator that contains double-layer permanent magnets is presented in this paper. To analyze the retaining-force change caused by the magnets, an equivalent magnetic circuit (EMC) model is established, while the EMC circuit of a double-layer permanent-magnet valve actuator (DLMVA) is also designed. Based on a 3D finite element method (FEM), the calculation model is built for the optimization of the key DLMVA parameters, and the valve-actuator optimization results are adopted for the improvement of the DLMVA design. A prototype actuator is manufactured, and the corresponding test results show that the actuator satisfies the requirements of a high retaining force under a volume limitation; furthermore, the design of the permanent magnets in the DLMVA allow for the attainment of both a high initial output force and a retaining force of more than 100 N.