The composition and method of the electrically controlled injection of LPG/Gasoline dual fuel system for motorcycle engine are introduced in this paper. The dual fuel engine's emission performance is tested and compared with the initial petrol engine. The indicator diagrams of the dual-fuel engine with different LPG injections are measured and analyzed. The experimental results show that both CO and HC emissions from the engine with LPG/Gasoline dual-fuel system are greatly decreased. Furthermore, when LPG injection is slightly changed, both output power and air-fuel ratio of the dual-fuel engine vary slightly but the emission performance is affected greatly.