Adjusting the density of low-energy boundary, i.e., Σ3ⁿ twin boundary, in a thermal-plastic deformation process is a significant approach to enhance grain boundary-related properties for an alloy. In order to uncover the distribution and evolution of twin boundary density in a current-heating forming process, and their inner mechanisms dependent on grain size and stored-energy, an electrical-thermal-mechanical multi-field coupling and macro-micro multi-scale coupling finite element model was established. Simulation results of isothermal compression processes for Ni80A superalloy show that twin-boundary density keeps constant in the heating and holding stages, while it increases quickly and then intends to decrease in the compressing stage. Its distribution gets more homogeneous under high temperature and medium strain rate. The processing parameter domains corresponding to finer grain size and higher stored-energy, as well as higher dynamic recrystallization degree, contribute to promoting the twin boundary density.