This system takes the detection of CO concentration in home environment as the object of research,and makes use of Internet of things and short message service of SIM900A to change shortcomings of existing CO alarm system that can’t achieve remote alarm,which designed a kind of remote CO alarm system of household that based on STM32.First ,by CO sensors and other sensing components and STM32 control chip to obtain the concentration of CO information.Then,real-time display of current CO concentration value via LCD display,and if the current value exceeds the threshold,the buzzer will work and send text messages to the emergency number which already set,thus can get help through this method. A lot of experimental results show that the system can real-time monitor the focus area changes of CO and stable running, get accurate data, realize the function of alarming and SMS messages.In addition, the system also has characteristics such as low cost, easy installation and maintenance, convenient operation.