DME and hydrogen were blended with air in intake and the HCCI combustion was realized. The speed of engine was hold at 1400r/min and the mass flow rate of DME was ranged at 2.6 and 3.5L/min. With the hydrogen fraction increasing, the excessive air coefficient λ was reduced until the engine knocked. The result showed that DME blended with hydrogen could increase the peak pressure, heat release rate and BMEP. The peak pressure was improved 26.4% when the DME flow was 3.5L/min. In the emissions, CO and HC could be reduced, and CO emission was only 20%~30% of the original data after hydrogen enriched. However, NOx emissions increased with the addition of hydrogen.