Different PVC compositions were compounded with different level of acrylonitrile butadiene rubber(NBR) and trimethylolpropane trimethacrylate(TMPTMA) as crosslinking agent to evaluate radiation sensitivity for gel formation and mechanical properties. When NRR and TMPTMA were mixed with PVC, the radiation dosage required for gel formation was found to be much smaller than normally plasticized PVC at room temperature. As TMPTMA content was increased, there was a progressive increase in gel formation up to 20 par of TMPTMA, then a slight increase in gel formation regardless of the addition of NBR. Normally plasticized PVC showed little change in tensile strength, modulus and elongation with irradiation but marked increases in tensile strength and modulus, and decrease in elongation were brought with adding of NBR or TMPTMA.