With the social development and progress, people in the pursuit of material increasing, and rang the doorbell-user needs in light of the realities of modern society and the needs of design, to meet people's demands. MCU control as the smart one of the products in the design of SCM opened a new field. This paper presents a new multi-functional doorbell of the principles and characteristics, using the SCM control of the police rang the doorbell and music players. Specific research is: MCU AT89S52 as the core, through the keyboard input to the SCM commands and then rang the doorbell of the SCM control music player and alarm. The design process, the use of simulation software and the Proteus-fu simulation software, to create successful products. This achievement has brought happiness to the people, improve people's quality of life.