The effects of irradiation atmosphere，irradiation dose，and heating rate upon the thermoluminescence of γ-irradiated polyethylene sheet were studied． It is found that off the glow curve there appear three main peaks between 77°K and 273°K with irradiation doses up to 9×105 rads，but the number of peaks is reduced to two as the dose is in-creased to or over 2×106 rads．At low irradiation dose

the effect of oxygen is pro-nounced，while peak I (the low temperature peak) seems to remain unchanged．Furthermore．an endothermal peak with its temperature location close to glow peak I，is observed on the DTA (differential thermal analysis) diagram of an irradia'ted poly- ethylene powder sample．Contrary to the glow peaks，this endothermal peak disappears after repeated irradiation，even on repeated DTA testing．This indicates that the glow peak I and the endothermal peak are of different origin．but it is considered that the factors determining the temperature locations for the appearance of these two peaks might be the same．By separating the main peaks from each other，the values of activation energy for peak I and III have been determined to be 0.22 eV and 1.2 eV respectively．However．the value for peak III is nearly identical with that obtained by the method of changing heating rate，while the difference between the values for peak I is fairly large．By tom-paring the experimental curve with the calculated ones，it is shown that the results ob-tained by the peak-separating method is more reasonable．