This paper describes a contactless method for evaluating the performance of a decoupling capacitor network and diagnose power integrity issues. A performance indicator is extracted for each capacitor from the near-field measurements (based on Z21 impedance measurement). Quantitative performance indicators extracted can provide in-depth analysis of the effect of the design of power network. The influence of each capacitor on the overall network impedance can be clearly identified and the impact of other contributors in the power network (PCB, IC and regulator) can also be analyzed. Using the near-field measurement allows to have a relevant approach (contactless, accurate and very wide band) to analyze decoupling capacitance network.