Abstract: Experiments were carrid out for thermodesorption measurement of 3He from metal tritides in a ultravacuum metal system. 3He analyses were performed by a quadrupole mass spectrometer (QMS). During thermal desorption, the metal system remained closed in vacuum. All gas pressures were measured by film manometer in desorption system. 3He was sampled by a leakage valve and measured by QMS. All data were displayed in integral form. The results of calibration of 4He in desorption system show that the correlation coefficient is more than 0.99 and the contribution of memory effect can be ignored. The contribution of ionized atom T+ for partial pressure of m/e=3 is very little and is determined according to I T+≈0.01I T2+, so the measurement of 3He can be done without interference of T+. The relationship between gases release rate and annealing temperature can be obtained after the data are smoothed and differentiated.