For the serious smoke emissions of diesel engine during the starting process, the starting smoke was optimized by improving combustion process and fuel property on a test bench. The results show that the speed of injection beginning , fuel injection quantity of starting and fuel property have direct impact on the smoke of starting process. Under the test conditions, increasing the speed of injection beginning, reducing the fuel injection quantity of starting and increasing the cetane number and oxygen content of fuel appropriately can reduce the starting smoke effectively.