Abstract: To get basic knowledge about the degradation of polyethylene (PE) to oils in supercritical water (SCW), the effects of reaction temperature, reaction time, water to PE ratio and water fill rate on the degradation of PE to oils were investigated in supercritical water with a 125mL autoclave. Reaction conditions were in the range of temperature 450℃~480℃, time 1min~30min, water/PE ratio 2/1~10/1 and water fill rate 25%~40%. The experiment results show that PE can be highly converted to liquid fuel and the temperature is the main factor effecting the decomposition of PE in SCW. The yield of oil decreases from 91.4% to 61.7% and that of gas increases from 1.9% to 27.7% with the increase of temperature from 450℃ to 480℃. A twofold increase of the yield of C7-11 hydrocarbons with the increase of reaction time from 10min to 30min is observed. The decomposition of PE is retarded to a certain extent due to the high water/PE ratio or high water fill rate. For increasing the productivity of the unit volume of reactor, keeping H2O/PE ratio at 2-4 is reasonable.