As an effective method to reduce the Common Mode (CM) Electromagnetic Interference (EMI) noise, the impedance balancing technique is utilized in different converters. In theory, this balancing technique could reduce the noise to zero. However, the practical result is not stable and suffered from challenges like the noise peak at high frequency. Based on a conventional boost converter, this paper introduces an accurate noise modeling method by identifying the noise source and propagation paths. The influence of high-frequency voltage ringing is also taken into consideration to improve the accuracy of this noise model. Then the modeling method is utilized to analyze the impedance balancing technique. Based on the noise expressions and the impedance information, the degree of noise source attenuation is investigated properly. In addition, this model helps to redesign the parameters of the balanced arms in quantitative. The optimized scheme improves performance effectively and avoids the noise peak problem. Experimental results are presented to demonstrate the feasibility and effectiveness of the proposed schemes.