Abstract: In this paper, the relationship of the degree of degradation of γ-irradiated 1,2-polybutadienes with various 1,2-unit contents to the radiation dose was studied. It is found that the sol fraction of the crosslinked samples is proportional to the β power of the radiation dose, and the lower the 1,2-unit content, the smaller the βvalue is. Since the molecular chain of 1,2-polybutadiene with lower 1,2-unit content is more flexible than that with higher content, radiation behaviour of 1,2-polybutadienes relates to their chain flexibility. It is proposed that structural parameters of polymer, such as cohesion energy density and cross-sectional area of polymer chain, could be used to relate to the parameter β, that is, to the effect of structure of polymer on the radiation behaviour.