The effectiveness of treeing resistance in low density polyethylene containing azocompounds were investigated under radiation environments. 4-(4-nitrophenylazo)-1-naphthol and 4-(4-nitrophenylazo) resorcinol were selected for treeing inhibitors. LDPE containing the additives were crosslinked with dicumyl peroxide, irradiated by $Co^{60}$ ${gamma}$-ray in the presence of air at room temperature. Treeing inception voltage, AC breakdown strength measurements were carried out for electrical insulation characteristics, thermoluminescence and gel contents were analyzed as various irradiation doses also. LDPE with treeing inhibitors showed much better insulation characteristics than pure LDPE. It is interpreted that molecular structures, polar groups and the type of radicals connected on the benzene ring of the additives affected electrical characteristics. From the results, 4-(4-nitrophenylazo) resorcinol was the most effective upon the best treeing and radiation resistance.