Abstract: In view of the difficulty in controlling the transient air fuel ratio of electronic controlled LPG engines accurately,a kind of air fuel ratio control strategy that combined the modified Elman neural network and the traditional PI controller was put forward in this paper.The Elman neural network was used to estimate the air fuel ratio signal without transfer delay.The traditional PI controller was used to control the transient air fuel ratio by using the estimated signal.To verify the validity of the control strategy,a simulation model for controlling the air fuel ratio of the electronic controlled LPG engine was set up,using GT-Power/Simulink.The simulation results showed a fair self-adaptability of this control strategy,which could keep the controlled error of the transient air fuel ratio within±5%.