This design studies a household intelligent anti-theft alarm based on 51 single chip technology. Anti-theft alarm device is a new type of passive infrared detector, which can detect infrared radiation emitted by human body in a non-contact way and convert it into corresponding electrical signal output. This function can effectively suppress human radiation. 89C51 single chip computer is the core of working processor and external thermoelectric infrared sensor. The interference of infrared and visible light exceeds the emission wavelength. Usually the sensor output low level, when someone moves in the detection area, the output low level becomes high level. The high level is input into the MCU as the external trigger signal processing of the MCU. The MCU is programmed by the internal software of the MCU, and the control signal is output to drive the photoacoustic alarm circuit to start the alarm. The most important characteristics of the alarm are easy operation, flexible understanding, convenient installation, high intelligence and low false alarm rate. With the enhancement of modern people's safety consciousness and the rapid development of science and technology,