A method and device for monitoring the safe distance between a lightning conductor and a tower involves establishing multiple models of different microtopographies and microclimates as well as tower models. By adjusting wind speed, wind direction, voltage, and current until the lightning conductor discharges, the critical conditions for the conductor's discharge under different microtopography and microclimate models, wind speeds, wind directions, voltages, and currents are obtained. Then, the distance between the conductor and the tower at the moment of discharge is determined. By plotting a three-dimensional curve of wind speed, voltage, and distance, the area formed by the voltage, wind speed, and the distance between the conductor and the tower on the curve represents the selectable distance between the conductor and the tower under those voltage and wind speed conditions. This distance is the safe distance between the conductor and the tower, which can provide the power line design unit with a reference for the spacing between the conductor and the tower, ensuring the safe operation of the power line.