Abstract: The equilibrium solubility for ethylene oxide in a high boiling point solvent was studied at 333~503K and 0.02~0.35MPa by determination of temperature T and total pressure P at equilibrium condition, and the equilibrium data for system were obtained by means of material balance and Peng Robinson equation of state. Through regressing the experimental data, the correlation equation of solubility of ethylene oxide and temperature was established. The relationship between equilibrium compositions to partial pressure of ethylene oxide and temperature were discussed respectively.The experimental results provide the basis for the determination of operating conditions of ethylene oxide synthesis in three phase bed.