In order to improve the low-temperature starting pace and stability of diesel engine, different amounts of ether were pre-injected into the intake port of diesel engine under the conditions of reducing the fuel amount of starting and increasing the starting resistance torque. The effects of ether promoting combustion on the number of starting cycles and the combustion and emission performance of diesel engines were studied. The results show that pre-injecting small amount of ether in the intake port has little effect on the number of starting cycles, but leads to the significant increase of maximum in-cylinder pressure and maximum pressure rise rate during the starting process after the fuel injection volume is calibrated. It is also found that preinjecting ether and reducing the fuel amount of starting can effectively improve the starting roughness of diesel engine. When reducing the fuel amount of starting and increasing the starting resistance torque simultaneously, the starting process accelerates with the advance of 3 to 5 cycles by pre-injecting ether in the inlet that accounts for 20% of the calorific value of the initial circulating fuel. The combustion process advances, the peak heat release rate and the pressure rise rate decrease, and the starting combustion process becomes more stable, but the HC and CO emissions of starting process increase after pre-injecting ether in the intake port.