The influence of unsaturation of various polyethylene on the radiation cross-linking, with and without polyfunctional monomers, was investigated. The results showed, that the suspended double-bonds of vinylidene has higher contribution to the radiation cross-linking. The polyethylene contained a bit more double-bonds possessed auto-sensibilized cross-linking action. The sensibilizing agent added outside posses has very small influence on the acceleration of radiation cross-linking.,The effects of three autioxidants (1010, 3114 and PG) on the radiation cross-linking efficiency of LDPE were studied. Experimental results showed, both 1010 and 3114 decreased the amount of crosslinking at a given dose, contrarily, the PG increased it. PG decomposed by radiation and produced OH radical which could accelerate the radiation cross-linking.,When the polyfunctional monomer was added to the system, the radiation cross-linking of LDPE containing 1010 was accelerated. However, for sample cotaining PG the sensibilizer exhibited very small influence on the radiation cross-linking.