Abstract: As the lightning downward leader approaching to the grounded objects,the upward leader launched by grounded objects is the main factor to affect the lightning strike targets and the lightning attractive radius of grounded objects.The simulation experiment is the major way to explore the characteristics of upward leaders and verify the effectiveness of direct lightning protection devices.The validation of the simulation experiment is determined by the similarity of the electric field spatial-temporal characteristics between the simulated one and the natural lightning attachment process.Based on the numerical calculation results of the spatial-temporal characteristics of the electric field in the vicinity of typical grounded objects during the downward leader approaching to ground,an equivalent simulation method was proposed in this paper.A high voltage impulse waveform generation method was introduced which could represent the temporal characteristics of the electric field.According to the theoretical analysis,a HV prototype generator was developed.The feasibility and effectiveness of the simulation method was validated by the prototype generator test results.The work carried out could provide a practical reference to the study of upward leader discharge characteristics and validation test method of direct lightning protection devices.