To investigate the mechanism of electrification from aero-engine jet and the electrification effect on the overall charging characteristics of vehicle, a simulation model of concentration of charged particles in aero-engine is build based on the equations of fluid motion. And concentration changes of various particles are simulated. To verify the simulation result, a special electrostatic induction sensor for detecting the electrification of engine jet is designed, according to the principle of the Faraday cup, to measure the dynamic potential when the turbofan engine starts, operates steadily, accelerates, decelerates and stops. The simulation and experimental results show that the aircraft is negatively charged by the electrification from aero-engine jet and the mechanism of electrification from aero-engine jet is described specifically. The research may provide a guidance to the further study on analyzing the overall charging characteristics of vehicle during the flight.