Lightning strike is one of the main causes of power transmission line tripping, with multiple lightning strikes accounting for 30% to 50% of the total lightning strikes. Under multiple lightning strikes, multiple lightning currents may invade the line, causing damage to substation equipment. Therefore, it is necessary to conduct research on the parameters and waveform of lightning multiple lightning strikes. This paper investigates a natural lightning current generation method based on conditional probability, and explores the complex multiple lightning phenomena. By modeling the randomness of lightning strikes, this method can simulate the characteristics of lightning current waveforms. In the experiment, a detailed analysis and description were conducted on the probability of lightning state transition, lightning current amplitude pattern, lightning current interval time, lightning current waveform parameters, and lightning flow channel impedance. By simulating the generated lightning current waveform, the method proposed in this article can conform to real natural laws and can be applied to the testing and verification of lightning induction and protection equipment, impact research, and the development of lightning detection and early warning systems. In addition, it can also provide a more realistic power supply for over-voltage Monte Carlo simulation to obtain the probability of over-voltage.