The invention relates to a universal method for detecting toxic gas and alarming and an instrument thereof. In the method, a basic module, a universal interface unit of a toxic gas sensor and a wireless communication universal interface unit are adopted. The basic module comprises a central processing unit, a one-key on/off and power supply management unit, a temperature and humidity detecting unit, a real-time clock unit, an alarm unit and a human-machine interface unit, and can be used for completing one-key on/off management, toxic gas detection signal processing, battery power detection, temperature and humidity signal processing, real-time clock signal processing, alarm control and strategy management, human-machine interface control and output wireless signal transmission management. The instrument integrates a toxic gas detection interface function, a temperature and humidity detection function, an alarming function of various manners, and various wireless communication interface functions into a whole, and is convenient to carry on and simple and convenient to operate, and toxic gas sensor modules and wireless communication modules of different manufacturers can be replaced as required.