In order to study the performance test technology of cesium ion bombarding microchanne plate， a cesium ion beam generator was used as an experimental device. To analyze the whole process of cesium ion beam generation and study the factors affecting the ionization efficiency of cesium plasma generated by cesium atom bombarding ionized filament （tantalum， with a desorption work of 4.12 eV）. From the physical process， it is found that the ionization efficiency is affected by the ionization environment temperature， the power of ionization filament and the focusing voltage. Combined with the of Saha-Langmuir equation， it is analyzed that the emitted ion current can be used as the actual characterization of the ionization efficiency. In the experiment， the ion current was measured by feedback current method of operational amplifier by changing the factors of ionization environment temperature and ionization filament power. The experimental results show that the number of cesium atoms can be kept stable by controlling the ionization environment temperature， and the ionization efficiency of cesium ion is greatly affected by the ionization environment temperature and the ionization filament power. When other working conditions remain unchanged， the ionization efficiency reaches the maximum when the ionization filament power Q_c is 2.818 W； when the ionization environment temperature T_c is 110℃， the ionization process is stable and the most sufficient， and the maximum output ion current is about 25 nA. The experimental results are in good agreement with the theoretical model. By controlling these factors， the incident intensity of cesium ion beam can be stably adjusted.