The kinetics of thermal degradation of styrene-butadiene rubber (SBR) was studied by conventional thermogravimetric technique with various heating rates under nitrogen. A kinetic model which accounts for the effects of scission of polymeric chain at any time was proposed to describe the thermal degradation of SBR. Results showed that the contribution of the thermal degradation of zero-order reaction is greater than that of first-order and second-order reactions. The activation energy of the thermal degradation of SBR was calculated to be 172kJ/mol using the Arrhenius equation.