Direct lightning strike seriously threatens the safety of power systems. With the development of lightning model and fractal theory, the lightning fractal model has been gradually applied to the shielding analysis of power systems, yet the reliability and accuracy of the model still lack experimental verification. In this paper, a series of lightning simulation tests were conducted based on rod-rod air gaps. By changing the configuration of the test gap, the attachment probabilities were obtained and the influence factors of the attachment probabilities were investigated. Upward discharges were also recorded and analyzed. The comparison of the simulation results and the experimental data shows that the overall trends of the attachment probability are basically consistent, and the average probability differences are within 10%. The lightning fractal model was therefore proved to be of good reliability in prediction of lightning strike probability.