The invention relates to a device and a method for calibrating a flow-dividing vacuum leaking hole, in particular to the device and the method for calibrating the vacuum leaking hole, the leakage value of which is less than 1*10-8 Pa.m3 / s by adopting flow-dividing technology, and belongs to the field of measuring technology. The device consists of the calibrated leaking hole, a valve, an
ionization gauge, a
small hole, a flow-dividing chamber, a non-evaporable
getter pump, an ultrahigh vacuum calibrating chamber, a metering hole, a very high
vacuum pumping chamber, an oil-free bi-turbo molecular pump air exhauster set, a
quadrupole mass spectrometer, a flow meter, a super-high vacuum calibrating chamber, the metering hole, a super-high
vacuum pumping chamber and a common molecular pump air exhauster set. The method adopts a fixed flow method gas micro-flow meter to provide a known gas flow rate, so the measuring range of the flow rate is wide and uncertainty of the measurement is low; and by adopting a flow-dividing method to calibrate the vacuum leaking hole, the method of the invention completely avoids a nonlinear error of the
quadrupole mass spectrometer and can precisely calibrate the vacuum leaking hole the leakage value of which is less than 1*10-8 Pa.m3 / s.