This graduation thesis design topic is a kind of infrared wireless burglar alarm designed on the basis of SCM technology. The burglar alarm processor by single chip microcomputer AT89C51, external pyroelectric red sensor, belong to the passive infrared detectors, can detect the human body within a certain distance from the infrared radiation, and translate them into corresponding electrical signal output, and at the same time can effectively suppress the radiation wavelength of infrared ray and visible light interference. In the normal working state, the sensor outputs low level. If someone moves within the detection area, the sensor generates a response output high level, and transmits the output control signal to the MCU for processing and processing, and then starts to emit alarm sound through the driving acousmo-optic alarm circuit. With the rapid development of science and technology, the function of burglar alarm is also constantly improved and people's safety awareness is constantly improved. The use of burglar alarm will be more and more popular to protect people's lives and property from loss.