The invention relates to an online
measurement device of gas
partial pressure and an online measurement method thereof. The online
measurement device comprises a to-be-measured gas source chamber, a
calibration gas source chamber, a
pressure reduction chamber, a
constant pressure chamber, a vacuum gauge and a
mass spectrometry module, wherein a
high pressure to-be-measured gas sample injection channel and a
medium pressure to-be-measured gas sample injection channel are arranged between a first intake valve and the
pressure reduction chamber, a low-pressure to-be-measured gas sample injectionchannel is arranged between the first intake valve and the
constant pressure chamber, a
calibration gas sample injection channel is arranged between a sixth intake valve and the
pressure reduction chamber, a gas circulation channel is arranged between the pressure reduction chamber and the
constant pressure chamber, the vacuum gauge is used for measuring vacuum degree of the four chambers above, and the
mass spectrometry module is used for online measurement for gas of the constant pressure chamber. The measurement method comprises steps of determining standard sample gas, performing cleanliness detection, acquiring
mass spectrometer sensitivity, performing
vacuum pumping to remove residual gas and performing online measurement of gas
partial pressure. The online
measurement device and theonline measurement method of the invention mainly aim at coarse and
low vacuum gas analysis, select an optimal sample injection channel according to pressure of the to-be-measured gas and are more accurate in
partial pressure measurement.