The indicator diagram was collected to study the effect of injector parameters and low pressure fuel supply system on cyclical combustion variation of DME as engine. The experimental results showed that the cyclical combustion variation of the DME engine decreased when the nozzle diameter hole diameter was increased. The influence of the nozzle hole on the cyclical combustion variation for the DME engine at high speed was more significant than that of low speed. The cyclical combustion variation increased when the opening pressure of the oil injector was increased at low speed, however it showed the opposite changing trend at high speed. The cyclical combustion variation decreased when the load of the engine was increased. The cyclical combustion variation coefficient showed a trend of first increase and then decrease when the fuel supply advance angle was advanced from BTDC 6°CA to BTDC 13°CA. The cyclical combustion variation could be controlled effectively by adding the volume of the accumulator of the low pressure fuel supply system.