On-line transformer monitoring device and on-line transformer monitoring method

The disclosure relates to an on-line transformer monitoring device and an on-line transformer monitoring method. The on-line transformer monitoring device comprises a degassing module, a gas detectionmodule, a processing control module and a protective shell. The protective shell is connected with a fluid container of a transformer, and a fluid passing opening is formed between the protective shell and the fluid container. The degassing module is arranged in the protective shell and used for isolating a part of space in the protective shell to form a gas detection chamber, and the degassing module is used for separating to-be-monitored fluid from gas dissolved in to-be-monitored fluid, so that the separated gas enters the gas detection chamber, and the separated fluid is isolated outsidethe gas detection chamber; the gas detection module is used for detecting gas in the gas detection chamber and transmitting detection data to the processing control module; the processing control module is in communication con