Abstract: Due to the limitation of the manufacturing process of high temperature superconducting tapes (HTS tapes), the length of a single HTS tape is usually tens of meters to hundreds of meters. In order to meet the needs of the length and current carrying capacity of superconducting wires in practical engineering applications such as HTS motors, lapped joints can be formed to join several HTS tapes, and these tapes are stacked and packaged to form HTS stacked wires with "inner encapsulated joints". However, the current distribution at the inner encapsulated joints will lead to complex characteristics of the overall resistance of the stacked wires. Therefore, in order to investigate the current distribution in the inner encapsulated joint of HTS stacked wires, a nonlinear circuit simulation model was proposed in this paper. Firstly, this paper analyzed three typical lap joint structures of single HTS tape, and established the equivalent circuit model based on the equivalent structure of an arched joint. Secondly, under different current conditions, this paper investigated the influence of copper layers on current distribution in stacked wires. Thirdly, based on the aforementioned research, a simplified model of stacked wires with two HTS layers was established. Based on this model, the phenomenon of "multi-linear resistance" of stacked wires with inner encapsulated joints was explained in detail. Finally, two improvement methods for stacked wires with defects on HTS layers were compared by using the model proposed in this paper. This study could provide a reference for analyzing current distribution in stacked wires with inner encapsulated joints, and provide guidance for future work of extending the length of stacked wires.