The reversion and chemical stress relaxation behaviour of natural rubber (NR) cured with equilibrium cure system (EC) were studied. The results manifested that the reversion and tensile strength decrease percentage of NR cured with EC after 6 hour were remarkably lower than that of NR cured with conventional vulcanization system (CV). The order of the amount of crosslinking bonds was EC>CV>SEV(semi -effective vulcanization system) during the process of chemical stress relaxation. The thermooxidative aging activation energy values of NR cured with EC

SEV and CV were 159. 5

141. 7 and 114. 6kJ/mol

and their tensile strength values were 26. 9

21. 6 and 24. 7MPa respectively. It could be inferred that one of the main reasons of lower reversion beyond 100 minute curing period was that the vul-canizate cured with EC had a good property of thermooxidative aging resistance.