A turbocharging lean burn LPG engine combustion model is set up by using three-dimensional simulation software. And the numerical simulation of the engine working process is done. Based on the model validation, the effect of the engine working process is calculated and analyzed by comparing with different ignition models (single spark ignition and dual spark ignition) and the simulation results are validated by experiments. The results show that: dual spark ignition (DSI) model as compared to single spark ignition (SSI) model can reduce flame propagation distance, form the stronger swirl rapidly, accelerate the flame propagation speed, reduce knock phenomena, reduce the emission temperature and improve the engine efficiency. Therefore, the engine has better power performance and fuel economy.