The holographic sensing capability of power systems is crucial for the establishment of a smart grid. Accurate acquisition of electric field data has vast application prospects, including non-contact voltage measurement, which is an important area of interest. However, accurate voltage inversion via electric field signals remains a challenging task at present. Numerical integration plays a critical role in inverting voltage signals by integrating the electric field of a specific node. In this paper, a comprehensive analysis is conducted on the distribution law of electric fields in transmission lines, taking into consideration the impact of height and wire radius on electric field distribution. The key influencing parameters of the numerical integration method for the electric field are also analyzed. The results indicate that reducing the wire radius from 5cm to 10cm leads to a decrease in the electric field coefficient from 4.4 to 3.9. When the height exceeds 10m, there is no significant change in either the wire radius or electric field coefficient within this region. Therefore, it can be concluded that the distribution law of the electric field remains unchanged. By utilizing numerical integration methods, an increase in integration nodes can significantly enhance voltage inversion accuracy. When utilizing six integration nodes, the voltage inversion error is a mere 0.19%. However, with increasing height, the accuracy of voltage inversion decreases and the relative error of each unit length measurement diminishes.