In an attempt to explore the effects of structure and mobility multiplicity of polymers on the mechanism of radiation crosslinking, the adaptability of Charlesby-Pinner’s equation and its various modified versions are examined. In the present paper, the effects of chain structure and state of aggregation on radiation crosslinking of polyethylene, polyethylene oxide and polyamides were studied with emphasis on the roles played by end groups, chain branches, and morphological factors. The experimental data of other polymers reported in the literature are also gathered and carefully analyzed. It is indicated that both chemical and morphological multiplicity of polymer structure result in the multiplicity of crosslinking mechanism, and which it is main reason of deviation between experimental date and those predicted by the Chharlesby-Pinner’s equation. The deviation at lower doses is closely associated with the structure and content of end groups of the polymer. In this stage, radiation crosslinking reaction takes place non-randomly. With the increase in radiation dose and the gradual consumption of end groups, the effect of end groups tends to become ignorable. Then the crosslinking reaction proceeds randomly, and the experimental date on this stage conform to the Chalesby-Pinner equation perfectly. Random crosslinking of main chain units is the characteristic reaction of amorphous phase only. When the radiation dose further increases, crosslinking takes place nonrandomly, since the Crosslinking reaction in interface of crystalline and amorphous phases.