The invention provides a lightning stroke risk assessment method and device based on cascade simulation. The method comprises: constructing a three-dimensional electric field model and a two-dimensional circuit model of a target area; inputting the three-dimensional electric field model into electromagnetic field simulation software to obtain electromagnetic field distribution in the three-dimensional electric field model under predetermined lightning stroke energy; converting the electromagnetic field distribution into a transient pulse waveform; inputting the two-dimensional circuit model into circuit simulation software, taking the transient pulse waveform as an energy source, and obtaining circuit response information; and carrying out lightning stroke risk assessment on the target area through the circuit response information. According to the lightning stroke risk assessment method and device based on cascade simulation, lightning strokes can be analyzed from multiple angles, andthe power supply reliability of the power distribution network is improved.