The deformation characteristics of soil under lightning impulse were studied. The shock wave theory was used to describe the lightning impulse pressure, and the expression for the electromagnetic force generated by lightning in the soil was derived based on Maxwell′s equations. Using Drucker-Prager elastic-plastic criterion, the finite element model of dynamic deformation characteristics of soil under lightning impulse pressure and electromagnetic force was established. The transient computation was performed to investigate the deformation characteristics of soil during lightning strikes, and the dynamic analysis of the deformation was carried out by combining the stress distribution characteristics in the soil. With the orthogonal analysis method, the influence of soil mechanical parameters on the model results and the ranking of primary and secondary factors were studied, and the influence of critical factors and lightning current peak was analyzed. Results show that under the action of lightning impulse, the deformation of soil increased sharply at first, then slowed down gradually, and tended to be stable after partial springback. In this process, the stress distribution in the soil was similar to the stress wave propagation. The internal friction angle and elastic modulus within the soil had more significant effect on the deformation, and a smaller value could cause a significant increase in deformation. The change in internal friction angle also affected the distribution law of vertical deformation curve of surface soil. In addition, the influence of electromagnetic force on soil deformation increased significantly with the increase in the peak value of lightning current.