With the data rate of digital ports is improved, the electrical specifications of the high-speed device under test (DUT）as AISC、SOC、ADC and DAC are severely affected by the test system’s signal integrity problem in the test. The test system’s Signal Integrity problem can leads to the difference between measurement results and actual electrical specifications. This paper proposed a method to avoid the signal integrity problem of test system by simulation and combined with good PCB design, analyzed and solved the problem of imperfect model. Through the signal integrity designing of a DUT test system and testing, verified the design method and modeling is validated.