Device and method for detecting harmful gas in exploration drilling layering

The invention provides a device and a method for detecting harmful gas in exploration drilling layering, and relates to the technical field of tunnel engineering, the device comprises a packing module, a water pumping module, a detection module and a processing module, an upper packer and a lower packer in the packing module are respectively connected with a water injection assembly, and the upper packer and the lower packer are respectively connected with the water injection assembly; the water pumping module and the detection module are located between the upper packer and the lower packer, the processing module is used for controlling the water injection assembly to inject water into the upper packer and the lower packer, and a closed detection cavity is obtained; controlling a water pumping module to pump water in the detection cavity to obtain a to-be-detected section; controlling the connecting assembly to place the sensor on the to-be-detected section for acquiring the concentration value of the harmfu