Abstract: Numerical simulations and experiments were carried out on the ion transfer rate of electron impact ion source(EI sources) developed by Lanzhou Institute of Physics.Using the simulation software Simon8.1, the influence of every electrode parameter of the EI source on its ion transfer rate was studied by using the control variable method, and the experimental verification was carried out, which proved that the experimental results were consistent with the simulation results.The results show that reducing the ionization chamber voltage, increasing the voltage difference between the ion-ization chamber and the ejecting pole, and adjusting the focusing pole voltage to the optimal value can improve the rate of EI source ion transfer.In a quadrupole mass spectrometer, the ionization chamber voltage and the ejecting pole voltage are affected by other relevant factors, and the adjustable range is very small, so the effective way to improve the rate of ion transfer of the EI source is to adjust the focusing pole voltage.