Abstract: Positron annihilation lifetime (PAL) and TEM were applied for the tritium charged HR-2 stainless steel to investigate the interaction between He and defects under heating process. For the samples without tritium, the results of PAL and TEM indicate that heating process induces the precipitates to form on the grain boundaries. For the tritium charged samples, when the temperature is less 300 ℃, He bubbles form by self-trappings, when the temperature is in the range of 300-600 ℃, He atoms which migrate to the grain boundary make boundary wider, on which no He bubbles are observed; when the temperature is more 600 ℃, thermal equilibrium vacancy becomes activity and combines with He atoms to form He bubbles which seem to combine and grow up with the increase of temperature.