This study was focused on the impact of the changes of the EGR rate on combustion, emissions and the coefficient of variation of LPG engine at lean burn conditions. Test data showed that dual-spark plug-based rapid burning system increased the combustion heat release of LPG mixture, and improved the rapid burning process of LPG engine with EGR. Meanwhile, the excess air ratio limits of LPG leanburning was largely extended within the total effective range of EGR rate（REGR）. At the equivalent running conditions of LPG engine, largely extended REGR restrained the formation of NOx emission by high combustion temperature. The highest REGR of rapid combustion process was increased from 5% to 811% of normal combustion process. Additionally, the coefficient of variation of LPG combustion process got control effectively.