In this paper, we studied on improvement radiated EMI of USB power line of cable. We confirmed the resonance in power line of cable through measurement of s-parameters. so, we confirmed the relation radiated EMI and power line of cable resonance and we reduced radiated EMI in power line of cable through a capacitor and low pass-band filter using the technique of power networks management. in conclusion, we suggested how to reduce power line of cable resonance applied for the improved method. and we confirmed that suggested reduction method is suitable through testing radiated EMI. the result of radiated EMI reduction limit criteria 40[dBuV/m] ~ 47[dBuV/m] in comparison to about 3 [dBuV/m] ~ 20 [dBuV/m].