Abstract: In this paper we present a numerical simulation programme about eddy current influences of waveguide pipe in pulsed magnetic field. We study effects of waveguide conductivity s , pipe radius R, wall thickness D R and excitation current angular frequency w on eddy current. Finally, we calculate influences of eddy current of stainless steel (1Cr18Ni9Ti) pipe which will be used in diode-relativistic klystron experiment.