The ultra-wideband pulse source is one of the key factors which decide the time-domain reflectometer’s specification including the testing bandwidth’s accuracy and veracity. Design a good pulse source is the major premise to improve the time-domain reflectometer’s performance. This paper introduced a new style of simulation realization using ADS2009. This simulation focused on the analyses of the importance of the pulse source in the time-domain reflectometer, described pulse source’s pivotal component step recover the diode’s characteristic and accomplished the modeling analyses.