Abstract: In practical applications the diameter and height of the induction coil have the same order of magnitude, hence the end effect is unnegligible in Iff (high frequency) plasma theory.The present paper calculates the electromagnetic field under the assumption of infinite plasma column with uniform conductivity.The results show that the magnetic induction differs greatly from that in vacuum case at axis, and even the direction is reversed in some cases.In contrast, the difference is not large at plasma surface, and the,phase lag between B and E there changes little, either.Hence, the EM field at the surface in vacuum case can be more adequately applied as boundary condition in HF plasma computation.