Abstract: Two apparatuses, open ion source and closed ion source quadrupole mass spectro meter(QMS), and their calibration are introduced in the paper. The 3 He released from tritium target is measured by these two apparatuses. The calibration results show that the measurement limitation of the former is 6×10 6 atoms, and 3×10 10 atoms for the latter. Both QMSs can measure the high dosage tritium target's 3He release. For the low dosage tritium target, only the open ion source QMS can be used to measure its 3 He release, and the uncertainty of measurement is about 7.2%.