Austenitic stainless steels 316L have been widely utilized for industrial application,especially,as the candidate structural materials for fusion reactor.It is well known that helium atoms can be trapped by several type defects,such as dislocations and vacancies,and would be formed to bubbles.In the present work,the effect of dislocation on helium retention in 316L stainless steel was investigated.In which the dislocations were introduced by cold rolling machine,and helium were produced by 50 keV He+irradiation at room temperature.Positron annihilation spectroscopy methods were performed to characterize the formation and behavior of defects and helium defect clusters.The positron annihilation lifetime and S parameters with positron energy will be used to demonstrate the detailed information and interaction of helium atoms with dislocation trapping sites.At the same time,the desorption energies of helium defect clusters were estimated from the thermal desorption spectroscopy.It shows that high density dislocation have stronger inhibitory effect for helium desorption at 800-1200 K.