The combustion and exhaust emission characteristics were investigated in an DME fueled HCCI engine with EEGR(external exhaust gas recirculation) and iEGR(internal exhaust gas recirculation). The effects of EEGR and iEGR on HCCI engine were compared each other under combustion and emission results. The effect of EEGR on HCCI engine was a contrary to the effect of iEGR. In case of increasing EEGR rate, start of auto-ignition was retarded and bum duration was extended. Due to these, indicated mean effective pressure was increased. Hydrocarbon(HC) and carbon monoxide(CO) were increased due to EEGR by low temperature of combustion. In case of increasing iEGR, start of auto-ignition was advanced and bum duration was reduced. Due to these, indicated mean effective pressure was decreased and pumping mean effective pressure was increased. HC and CO were decreased due to iEGR by increasing mixture temperature.