The invention discloses a 
system for pre-testing and diagnosing the electro magnetic interference of 
electronic equipment, which is characterized by comprising a 
data collecting module, an interference source diagnosing and locating module, an 
environmental noise eliminating module and a visual time-frequency analyzer, wherein the 
data collecting module, the interference source diagnosing and locating module and the 
environmental noise eliminating module are respectively connected with the visual time-frequency analyzer, and the visual time-frequency analyzer achieves the drive of the 
data collecting module, the call of the interference source diagnosing and locating module and the 
environmental noise eliminating module and the monitoring and displaying of time-domain waveforms and frequency spectrums. The invention also discloses a method for pre-testing and diagnosing the electro magnetic interference of 
electronic equipment, which utilizes a LabView visual instrument platform and 
Matlab programming environmental developing 
software to pre-test and diagnose signals. The invention can pre-test and diagnose the electro magnetic interference of 
electronic equipment at common test fields, and has high 
automation and carrying degree and simple usage and reduces cost.