Due to the uncertainty states of diodes in DC-DC converters, they may operate in various continuous conduction mode (CCM) and discontinuous conduction mode (DCM). However, the traditional manual analysis method is not only inefficient as a number of equations are required to be manually formulated and solved, but also incomplete since only a certain set of operations is generally considered. Aiming to avoid these disadvantages, a computer-aided automatic analysis method of DC-DC converters is proposed in this paper. It combines electrical network theory (ENT) with fundamental circuit law (FCL) and power electronics principle (PEP) to automatically explore all the workable operations of the converter and obtain their corresponding steady-state performance analysis results, which contributes to a comprehensive understanding for DC-DC converters. Then, the feasibility of the proposed computer-aided automatic analysis method was demonstrated with a single-input dual-output (SIDO) Cuk converter.