Abstract: This paper presents the structure and principle of a new lock mechanism and analyzes the key structure parameters affecting the performance of the new lock mechanism. Stability of lock state are maintained by the resilience of compression spring, stability of unlock state are maintained by the resilience moment of double torsion spring. Prototype test demonstrates that the auto-lock performance of the lock mechanism is stable and reliable. Finally, a typical application instance is given. This lock mechanism can be widely used in modern fast-mobile ground radars to effectively enhance the performance of automatic up and down. It is an important method for improving radar maneuverability.