Abstract: The diffusion-reaction models for the bi-functional catalyst for one-step dimethyl ether (DME) synthesis from syngas were established by using CO, CO2 and DME as key components and choosing the hydration of CO and CO2 and dehydration of methanol as key reactions. The macro-reaction rates and internal diffusion efficiency factors of key compounds were measured in an internal recycle gradientless reactor with the reaction temperature of 220-260 ℃, pressure of 5 MPa, and space velocity of 1 000-2 500 h-1. The internal diffusion efficiency factors of three key components were approximately between 0.11 and 0.64, which means that the internal diffusion affect the reactions seriously. The average of absolute value of relative deviations between calculated results by solving the diffusion-reaction model with orthogonal configuration method and the experimental data is within 10%, which means the models were acceptable. The effect of concentration profile of key components in catalysts and temperature on internal diffusion efficiency factors were also discussed.