In the aerospace power module, the voltage value of the line is as high as 300 V, which requires good insulation between the lines. The insulation resistance between lines is not likely to be an ideal state due to various factors influenced in the manufacturing process of flexible circuits. In particular, the seed layer between the lines would strengthen the conduction capacity between the flexible lines, thus the resin insulation between the lines is weakened. In this paper, the high-voltage conductive anode filament (CAF) high-current transmission requirements are established, and the corresponding high-voltage breakdown model is established to compare the CAF resistance of flexible circuits at different distances between lines by COMSOL. In addition, a model with or without polyimide as the medium is established to compare the line loss at a high current of 10 A. At the same time, we varied the thickness of polyimide in the model to study the temperature change around the circuit. The simulation results show that the spacing between the lines is 2 mm under high current, regardless of whether there is a seed layer between the lines, the lines have good breakdown resistance, which provides an overall solution for the design of flexible circuits.