In order to improve the throttle response speed and the following characteristics, a particle swarm optimization (PSO) based method was proposed to optimize the non-singular fast terminal sliding mode control (NFTSMC) in plug-in automotive electronic throttle system. Firstly, considering the parameter uncertainty of throttle components and the intake disturbance, the system disturbance is estimated and fed into the controller. Then the parameters of NFTSMC are adjusted by PSO algorithm, and the stability is proved according to Lyapunov′s second theorem. Compared with PSO-SMC, the response time of PSO-NFTSMC is reduced by 82 ms, the maximum value following error is reduced from 0.32° to 0.005°, and the maximum value of error is reduced from 0.5° to 0.004°. It is proved that the proposed plug-in automotive electronic throttle system under the control of PSO-NFTSM has faster response speed and more consistent with the preset error. The proposal and application of this method provide a reference for improving the combustion and emission efficiency of plug-in vehicle engines and improving the dynamic performance of vehicles.