Due to the sudden and transient of lightning

the strong electromagnetic pulse field of lightning is difficult to be directly measured

resulting in that it takes great difficulty to the research of lightning electromagnetic field.This paper decomposes the micro dipole into the one perpendicular to the earth and the other one parallel to the earth

using pulse function to express channel bottom current and combining with the TL model for lightning electromagnetic field

then the analytical expressions of electromagnetic field which is generated by oblique channel is obtained based on the dipole method to solve the Maxwell’s equations.The effects of channel height on lightning electromagnetic fields at ground surface based on oblique discharge channel model in different areas are researched.The results show that the impact of electromagnetic fields by channel height will increase with the increasing of the horizontal distance and the waveform of electromagnetic fields will overlap before the return stroke current reach the top of the channel.