Abstract: Objective: To address the issues of unstable parking braking force, fatigueinduced attenuation of parking braking force, and the complex mechanical structure in the spring parking braking devices for existing rail transit vehicle, a new type of air parking braking system is designed. Method: The structural composition and functional principles of the spring parking braking system are introduced. The above composition and principles of air parking braking system are also presented, along with an analysis of its system characteristics. The characteristics of new air parking system are analyzed. Result & Conclusion: The proposed new air parking braking system could change the operating mode of the service brake cylinder, transform the output force of the brake cylinder into the parking braking force. When compressed air is introduced into the parking cylinder, the internal spring of it is compressed, keeping the parking cylinder separated from the pull rod. At the same time, the nonselflocking thread remains in unlocked state. In this state, the brake cylinder performs service braking and service braking release. When there is no compressed air in the parking cylinder, the parking cylinder is tightened against the pull rod, and the nonselflocking thread is unidirectionally locked. In this condition, the parking cylinder locks the brake cylinder at the maximum stroke, preventing it from retracting and achieving the parking braking function. A twoway valve is installed between the service braking control module and the parking braking control module, with one outlet of the twoway valve connected to the brake cylinder, and another outlet of the parking braking control module connected to the parking cylinder. When applying parking braking, compressed air supplied by the parking braking control module is introduced into the brake cylinder. This system ensures consistent parking braking force for all air parking compound braking devices in the entire train, and allows flexible adjustment of individual parking braking force as needed. It also maintains longterm stability of the parking braking force and eliminates the risk of simultaneous superimposition of spring parking force and air braking force in the existing system.