Single‐electrode triboelectric nanogenerators (SETENGs) significantly expand the application of triboelectric nanogenerators in various circumstances, such as touch‐pad technologies. In this work, a theoretical model of SETENGs is presented with in‐depth interpretation and analysis of their working principle. Electrostatic shield effect from the primary electrode is the main consideration in the design of such SETENGs. On the basis of this analysis, the impacts of two important structural parameters, that is, the electrode gap distance and the area size, on the output performance are theoretically investigated. An optimized electrode gap distance and an optimized area size are observed to provide a maximum transit output power. Parallel connection of multiple SETENGs with micro‐scale size and relatively larger spacing should be utilized as the scaling‐up strategy. The discussion of the basic working principle and the influence of structural parameters on the whole performance of the device can serve as an important guidance for rational design of the device structure towards the optimum output in specific applications. A comprehensive theoretical model is developed for single‐electrode triboelectric nanogenerators. The real time output characteristics are calculated by different numerical calculation methods. A three‐capacitance equivalent circuit model is built to clarify the working principle of single‐electrode triboelectric nanogenerators. Finally, the impact of electrode gap distance and area size on the performance of the devices are investigated and strategies for the structural optimization are provided.