The chlorine dioxide gas monitor is used for real-time monitoring of the residual gas in the environment in various medical articles, medical consumables production units, pharmaceutical factories, disinfection supply centers or operating rooms, and alarms when the concentration exceeds the standard. The gas monitor can monitor the residual gas concentration in the air in the room. When the concentration reaches or exceeds the preset alarm threshold, the monitor will send out an audible and visual alarm. It can be used with remote gas alarm controllers or exhaust facilities such as fans. Linkage, promptly reminding operators to take safety measures to prevent explosion and poisoning accidents, so as to ensure the safety of life and property, it is the safety guarantee for the use of toxic gas sterilization equipment on site.