The bus technologies,especially the external bus technologies take a very important part in the instrument ATS,and are also considered as the bridge and tache of the ATS.This paper introduces several external buses which are usually used in the military ATS,and compares the capabilities of them.At last,by analysing the future development trend of the test bus technologies,the results can be got that the USB bus and the buses which are of the high throughput and long transmitting distance are the future deve...