As an easy-come and clean way to harvest energy，triboelectric nanogenerators have demonstrated a high application value in small self-powered system and sensors. Especially，triboelectric nanogenerators with unparalel structure have been widely experimentally designed in the contact-mode.Here，a systematical theoretical study of unparallel contact-mode triboelectric nanogenerators was constructed based on the equivalent circuit model.The equivalent capacitance and the control equation for analyzing output chracteristics was derived for the unparalel structure cases.By numerical simulation，the relationship between output voltage，current，power and the moving trail was further studied.Finally，an experiment was designed to verify the obtained conclusions，demonstrating a high degree of consistency with the theory.The results may supply important theoretical basis for rational design of the triboelectric nanogenerators structure.