Abstract: The problem of excess production capacity of ethylene glycol and methanol in condition of the rapid development of the coal chemical industry, made the dehydration conversion of the two into ethylene glycol methyl ether become a research hotspot. The thermodynamic equilibrium calculations for the heterogeneous dehydration process of ethylene glycol and methanol were optimized based on the Gibbs free energy minimization principle using a modified genetic algorithm in the manuscript. Under the conditions of ethylene glycol feed of 100 mol, 20-300℃, 0.1-0.7 MPa, and the feed amount of substance ratio of methanol to ethylene glycol is 1∶2-6∶1, the effects of temperature, pressure, and feed amount of substance ratio on the equilibrium conversion of reactants, product selectivity, and gas-liquid phase equilibrium composition were examined. The results show that under the conditions of 0.3 MPa and feed amount of substance ratio of 3∶1, within the gas-liquid coexistence range of 60-120 ℃, the highest conversion of ethylene glycol and selectivity of ethylene glycol dimethyl ether are 99.99% and 99.97%, respectively. Increasing pressure affects the temperature range in which conversion and selectivity change, but the overall trend remains unchanged. Increasing the feed amount of substance ratio increases the conversion of ethylene glycol to near 100% and improves the selectivity of ethylene glycol dimethyl ether, and narrowes the temperature range of the heterogeneous range from 40 ℃ to 20 ℃.