The accelerated thermal aging of CSPE (chlorosulfonated polyethylene) was carried out for 40.41, 121.22, and 202.04 days at $100^{circ}C$, which are equivalent to 20, 60, and 100years of aging at $50^{circ}C$, respectively. The volume electrical resistivities of the accelerated thermally aged CSPE samples for 0, 40.41, 121.22, and 202.04 days were $1.107{ imes}10^{14}-2.097{ imes}10^{14}$, $7.752{ imes}10^{13}-1.556{ imes}10^{14}$, $7.693{ imes}10^{13}-1.521{ imes}10^{14}$, and $7.380{ imes}10^{13}-1.304{ imes}10^{14}{Omega}{cdot}cm$, respectively, at room temperature. The permittivities of the accelerated thermally aged CSPE samples for 0, 40.41, 121.22, and 202.04 days were $2.89{ imes}10^{-11}-3.65{ imes}10^{-11}$, $3.40{ imes}10^{-11}-3.70{ imes}10^{-11}$, $3.50{ imes}10^{-11}-3.82{ imes}10^{-11}$, and $3.76{ imes}10^{-11}-4.13{ imes}10^{-11}$ F/m, respectively, at room temperature. The EAB (elongation at break) of the accelerated thermally aged CSPE samples for 0, 40.41, 121.22, and 202.04 days were 98.8-101.3, 59.5-60.3, 37.8-39.2, and 41.8-44.3%, respectively, at room temperature. The apparent densities of the accelerated thermally aged CSPE samples for 0, 40.41, 121.22, and 202.04 days were 1.603-1.614, 1.611-1.613, 1.622-1.628, and $1.618-1.620g/cm^3$, respectively, at room temperature. The measured currents of the accelerated thermally aged CSPE and the standard sample were almost constant after 5 min of applying a 300-V/mm electric field to the CSPE. The V-I slope of the accelerated thermally aged CSPE sample was increased if the applied electric field was increased at room temperature, and the V-I slope of the accelerated thermally aged CSPE was higher than that of standard CSPE.