Abstract: The photodegradation behavior of poly(ethylene oxide) (PEO) aqueous solution from 20 ℃ to 40 ℃ was studied by Gel permeation chromatograph (GPC) and computational simulation. The number of average chain scission and the number of scission events per gram of irradiation time was investigated. The relationship between the change of number average molecular weight with irradiation time and the degradation rate constant was established. The process of molecular chain scission was simulated by Python. The results show that the number of average chain scission and the number of scission events per gram increases with temperature increase, and showed a linear relationship with irradiation time. The activation energy of PEO degradation in aqueous solution is 19.8 kJ/mol. The Polymer dispersity index (PDI) of random chain scission did not change with time, but the PDI of intermediate chain scission decreased with the time. Compared with GPC results indicates that PEO photodegradation accords with the intermediate chain scission mechanism.