Computers have accelerated the transformation of the world's human pace, but it is after all bulky. SCM in this case was born. As of today, SCM application rapid development of technology, looking around us now in all spheres of life, from missiles, navigation equipment, to the various instruments on the aircraft control from a computer network communications and data transmission, industrial automation to real-time process control and data processing, and our lives extensive use of the smart card, electronic pets, which is inseparable from the microcontroller. Monolithic single-chip micro-computer or computer. (Single-Chip Microcomputer) is the set of CPU, RAM, ROM, the timing, number and variety of interface integrated microcontrollers. Its small size, low cost, high performance, which are widely used in smart industries, and industrial automation. And 51 Series SCM SCM is the most typical and the most representative one. The graduation design Through the study, and thereby achieve the study, design, development hardware and software capabilities. Based on a microcontroller based on the will to achieve timing, stopwatch, calendar, alarm clocks, and other functions of a multi-functional electronic clock design study, in detail, the computer application of data conversion, Principle LCD, keyboard scanning principle, SCM regularly interrupted principle. Thereby achieve studying and understanding the relevant directives SCM in all aspects of the application. By AT89S52 system, temperature detection chip, the clock chips, liquid crystal displays, memory, Regulators and electricity supply of components, to achieve clock calendar display function can be carried out, hours seconds of the show and real-time temperature display. Also calculated with the calendar and clock, calendar calibration, regular hours and set the alarm function. The article attached circuit diagram, the PCB plans and procedures checklist for the reference of our readers. Due to limited, and it will inevitably be lighter inadequate, locations will give teachers and students correction and criticism. Keywords : stopwatch, alarm clock, calendar time