The synergy effect of process coupling of reaction-reaction and reaction-heat transfer for dimethyl ether synthesis has been studied. The theoretical and experimental analyses show that the synergy of reaction-reaction is prominent and that the synergy of reaction-heat transfer is also feasible. Due to the synergy effect, CO-rich synthesis gas can be used for dimethyl ether synthesis and higher once-through conversion of CO can be obtained. Recycling and compression of the unreacted synthesis gas can be minimized considerably. Accordingly, savings will be made in energy consumption and the water gas shift reaction system, and the entire investment and production cost will decrease.