Abstract: Microdosimetry plays an important role in the clinical application of alpha-particle radioimmunotherapy. There is increasing interest to develop a set of microdosimetric model, which can exactly describe the nonuniformly distribution of dose at cellular or sub-cellular level as well as can be conveniently used in clinic. In this paper, introduce some common methods of microdosimetry and some important affective factors reported in current researches on alpha-particle radioimmunotherapy.