Characteristics of induced voltage in a horizontal conductor due to a natural lightning with 9 dart leader/return stroke sequence were analyzed. Effect of various parameters on the induced voltage was examined by numerical simulation. The induced voltage varied from a minimum of 4.6 kV to a maximum of 18.6 kV with a geometric mean of 11.2 kV. The geometric mean of the half-peak width and the down time of the induced voltage was 0.87 and 2.9 μs, respectively. The simulated results showed that the induced voltage on both ends of the horizontal conductor would increase with increasing return stroke velocity and also increase with increasing height of the horizontal conductor. The voltage would also increase with increasing of the matched grounding impedances on both ends of the horizontal conductor but the relationship was nonlinear. The induced voltage at the higher impedance end was much larger than that at the lower impedance one provided that the impedances at both ends were not matched, which indicates that good grounding can decrease effectively the induced voltage along the conductor.