Abstract: In this paper，the problem about setting initial field of log-periodic dipole antenna（LPDA）in electromagnetic wave propagation is studied. A new method that uses antenna current to set initial field of parabolic equation has been proposed，which solved the problem that the aperture cannot support the initial field in low mounted height of antenna conditions through traditional methods. A direct connection has been built between initial field and antenna current distribution. Using the new method，propagation factors of two pairs of LPDA under different conditions are calculated，and the results show the new method’s feasibility and effectiveness.