Experimental study on the combustion and emission performance of turbocharged lean-burned CNG engine by the ignition time. Speed of the engine is 1340r/min,1615r/min,1890r/min,with 25%, 50%,75%,100% load. Results show that when keeping other combustion boundary conditions unchanged, the effect of the ignition time on engine output torque and CH4 is little,the effect changes as speed varies from low speed and load conditions to higher level.However,the effects of ignition time on NOx emissions are huge.With the backward changes of the ignition time,NOx emissions has decreased significantly.