In this work, the effect of ignition modes on engine performance is discussed in detail. Torque, ECR (energy consumption rate), emissions and knock are investigated by using combining experiment with CFD (computational fluid dynamics). The results are as following: the torque of synchronous twin-spark is more excellent (for example, the torque improves by 2.3% under 60% engine load and 5000 rpm) relative to single-spark or the asynchronous ignition mode of twin-spark; the synchronous twin-spark ignition mode has shorter combustion period and less heat transfer loss, resulting in the lower ECR (under 60% engine load and 5000 rpm, it decreases by 3.7%).; unexpectedly all the emissions of synchronous twin-spark are higher (increased by 12%, 53.1% and 9.4% for HC, CO and NOx, respectively under 60% engine load, 5000 rpm) than those of single-spark. Then, we used CFD to reveal the seemingly contradictory phenomenon. And found that, under synchronous twin-spark mode, due to the specifically interaction form between flame and turbulence, the maximum in-cylinder temperature is higher and it decreases faster. This results in specifically pollutants formation patterns. The investigation provides a deeply understanding of in-cylinder working process under multi-ignition, and gives us a foundation for the optimization of ignition modes. (C) 2019 Elsevier Ltd. All rights reserved.