Nitrogen oxide measuring instrument with particulate matter filtering membrane capable of being automatically replaced

The invention discloses a nitrogen oxide measuring instrument with a particulate matter filtering membrane capable of being automatically replaced. The measuring instrument comprises a fixed plate, areplacement device is fixedly arranged on the left end surface of the fixed plate, an auxiliary plate is fixedly arranged on the left end surface of the fixed plate, a particle filtering membrane storage device is fixedly arranged on the upper end surface of the auxiliary plate, a first sliding groove cavity with a leftward opening is formed in the auxiliary plate, a dismounting device and a moving device are arranged in the first sliding groove cavity. The devices are installed inside a measuring instrument, a floater flow meter is inserted into the instrument, when the particle filter membrane needs to be replaced, the particle filter membrane can be automatically replaced due to the fact that the automation degree of the device is too high, the accuracy of measured data is greatly guaranteed, the working intens