The screen lock of touch screen devices is designed to prevent the users' misuse without taking security into account. To solve this problem, this study provides a design of a secure scheme to unlock the touch screen. Unlike the traditional modes that unlock the touch screen by sliding the sliders or identifying the graphics and images, the presented design is a method to create a rhythm key based on the tapping gestures. The rhythm recognition algorithm is able to identify the rhythm sequence tapped on the screen, extracting rhythm features and creating the keys. Through testing, the new scheme can better match the rhythm gestures and improve the information security greatly. Meanwhile, as a new unlock method and relating to the individual's sense of music experience, the rhythm recognition focus on users' experience such as convenience, entertainment and reliability, all of which are human-computer interaction-friendly features.