The experimental investigation on a LPG single fuel engine,which is refitted from a 188 gasoline engine was carried out.The LPG supply system was designed and the ignition system was improved according to the requirements of LPG and the flow characteristic of the LPG injector was calibrated.The effects of different compression ratios and spark advance angles on the performance and(emission) of the LPG engine were studied.Through the designed control system,the quantity of injected LPG and ignition timing in different operations can be controlled automatically.In the light of the engine tests,the contrast of the performance of the LPG and the gasoline engine was carried out.