Capacitors are ubiquitous in electronic devices and play a critical role in the devices' electromagnetic compatibility performance. The ageing of capacitors, due to intrinsic degradation mechanisms and external thermal and electrical stresses, has drawn a wide attention in the reliability field. The variations of the capacitance and equivalent series resistance are typically seen as representative for the ageing of capacitors, while the other parasitic parameters are usually neglected. In this study, a new full-parameter ageing modelling approach of capacitors is proposed based on complex impedance analysis. The ageing characteristics of all the proposed 7 parameters, including all parasitic parameters, are identified by carrying out an electrical overstress accelerated ageing test.