Multi-output DC-DC converters have simulated widespread interest considering some advantages such as plain circuit configuration, low cost and high conversion efficiency, which are incomparable with conventional multi-output technology. The purpose of this paper is to study the topology derivation approach of non-isolated multi-output DC-DC converters. Firstly, two types of basic output cells named voltage-type output cell (VOC) and current-type output cell (COC) are extracted from six basic dc-dc converters. According to the circuit principle and the duality principle, the topology structures of parallel-type VOC, series-type VOC, parallel-type COC and series-type COC are proposed. Secondly, a systematic derivation approach for multi-output converters is introduced. Furthermore, taking a proposed dual-output SEPIC converter derived from series-type VOC as an example, the operating principle, static and DCM characteristics of the proposed converter is studied. Finally, experiments have been carried out, which demonstrate the validity of the proposed topology derivation approach.