In order to know the breakdown theory of gas discharge and collect the optical single of needle －plate DC stream discharge in short air gap，we designed this experiment． Use optical fiber，spectrometer and ICCDto compose the optical single collecting system，the ICCD alone can capture the optical phenomenon and it can get the spectrum with the help of spectrometer． The controller of this system adopts outer trigger mode with highspeedtrigger pulse to get the images． The experiment analyzes the physical process of the phenomenon in the end．