Abstract: The slurry reactor with inert liquid can transfer heat in time and avoid the catalysts sintering, CO rich synthesis gas can be used in this reactor. In order to maintain both effective heat transfer and higher CO conversion, a slurry reactor in tandem with a fixed-bed reactor was used for DME synthesis. The synthesis gas was pre-mixed in a pressurized gas cylinder. The high pressure syngas was regulated and its flow rate was controlled by a mass flowmeter and fed to the reactor. The reaction pressure was kept by a back pressure regulator. The reactor effluent was analyzed on-line by two gas chromatographs. The experiments were carried out in the range of 220 ℃～260 ℃, 3.0 MPa～7.0 MPa and 500 mL·g-1·h-1～2 000 mL·g-1·h-1. The catalyst was a physical mixture of commercial methanol synthesis catalyst and methanol dehydration catalyst, the granularity was 0.15 mm～0.18 mm. The experimental results showed that the conversion of CO increased with increasing reaction temperature and pressure, the selectivity of DME was insensitive to temperature and pressure. 7.0 MPa and 260 ℃ were the optimal reaction conditions, at which 84.5% of CO conversion and 78.7% of DME selectivity were obtained while the the weight ratio of the catalysts loaded in the two reactors was 1∶1. Then DME synthesis reactions carried out in a fixed-bed reactor, a slurry reactor and the slurry-fixed-bed equipment respectively were compared and the adiabatic temperature rise of syngas was calculated. The results demonstrated that higher CO conversion was obtained in the slurry-fixed-bed equipment and the high temperature of hotspot was avoided simultaneously. Moreover, the catalyst was stable in the reactor during the 370 h reaction.