The present invention is related to a plug-in air quality detector, a control method and a control circuit, which pertain to the field of air quality detection. The plug-in air quality detector comprises a casing, a sensor component, a control circuit and a connector component. The connector component comprises a power supply terminal and a data terminal, and is configured to connect the plug-in air quality detector with a user device. As such, the detector can prompt a user of the air quality around him/her without being configured with a dedicated power supply and a dedicated display screen, thereby achieving the effects of reducing the size and the weight of the air quality detector and improving the ease of use.