Abstract: Evaluating the shielding effectiveness of cabins is important for verifying the susceptibility of systems against high altitude electromagnetic pulses. To quantitatively estimate the uncertainty introduced by experiment designs and data analysis, the method of evaluation is studied, which focuses on the selection of frequency or time domain measurement, the determination of test frequencies, the design of pass/fail curve, and the criteria to deal with unqualified points. A group of pass/fail curves for cabins with low shielding effectiveness are proposed. Based on the approximation of two order resonance systems, the uncertainty introduced by test frequencies, pass/fail curve, and the criteria are estimated, which provide sustainment for the experiment design, data analysis and the uncertainty estimation for evaluating the shield effectiveness of cabins.