Differential pair routing on PCB level is widely used as interconnect due to excellent performance in signal integrity. However, differential pair routing is not perfectly immune to the impact of routing discontinuities. This paper is about study the impact of differential pair microstrip with routing discontinuities. There are two types of routing discontinuities are discussed which are routing over split plane and routing over void. The results of this research are based on HFSS Fullwave 3D modeling and analysis simulation. There are three type of analysis are discussed for each of routing discontinuities which are S-parameter, TDR and Full-Path Analysis. The cross-sectional configuration parameter is based on SATA3 industrial standard design. Based on this research design parameters of split plane and void, the results show that the impact of differential pair routing with routing discontinuities degrades the signal integrity performance.