Locks have been used in ancient China for several thousands of years. However, the historic records of Chinese locks are few and the literatures regarding the design considerations are not available. This work introduces the development and mechanisms of ancient Chinese padlocks and to present the design considerations including: specifications, opening methods, keyhole positions, configurations of spring mechanisms, shapes of keyheads and keyholes, appearance with suitable material, and engraving patterns on the lock surfaces. And, through the steps of handicraft, the ancient locks are endowed with rich vitality and technological values.