CO2 incubator is an advanced instrument for cell, tissue, and bacterial culture, and is a key equipment necessary for immunology, oncology, genetics, and bioengineering. CO2 incubator is an improved version of ordinary culture, mainly capable of adding CO2 to meet the environment required for microbial cultivation. The control of CO2 concentration in CO2 incubators is achieved through CO2 concentration sensors. The CO2 sensor is used to detect the concentration of CO2 inside the box and transmit the detection results to control circuits and solenoid valves. If the CO2 concentration inside the box is detected to be too low, the solenoid valve opens and CO2 enters the box until the CO2 concentration reaches the set concentration. At this point, the solenoid valve closes and CO2 inside the box is cut off, reaching a stable state.