Abstract: A direct-travel electric actuator was designed, which is composed of a frameless torque motor, planetary roller screw, cylinder, electromagnetic brake and encoder, etc. The spatial multiplexing form was adopted to significantly reduce the size and weight of the actuator. The direct drive scheme of frameless torque motor and planetary roller screw was adopted. By integrating a 23-bit multi-turn absolute value encoder and electromagnetic-mechanical dual-mode braking system, it has precise repeat positioning accuracy, and can output a rated thrust of 3.5kN within an effective stroke of 22mm, with a maximum operating speed of 25mm/s. Through optimizing the design of each component and using domestic components, the actuator can operate stably within the temperature range of -40°C to 85°C. The performance indicators of this actuator fully meet the strict requirements of the industrial automation field. This paper elaborates in detail the working principle, structural design, performance characteristics and environmental adaptability of the actuator, providing technical references for the research and development of similar products.