Such components as the line and transformer are usually regarded as the analysis units in many methods for evaluating the reliability of complex electrical distribution networks（EDNs）. A switch-oriented algorithm is proposed from a novel perspective. This method views switches used for disconnecting the failed component as the analysis unit. The definition of coupled-switches（CS） and the traversal algorithm for CSs using the depth-first method are proposed. The algorithm developed regards the CS as a unit during the computing process of reliability evaluation. Based on the information about CSs distribution and the structure of EDN， it is easy to identify a disconnected section and controlling CSs， following which the nodal classification of the nodes is obtained. The reliability indices of the buses， feeders and system are calculated according to the nodal classification and the equivalent reliability parameters. The algorithm developed has been tested on the RBTS and a number of practical EDNs with the effectiveness and applicability of the approach shown by the results.