  (This is a recompiled version of $Chin. J. of Phys., Vol. 26, No. 4, 180$
since the previous available electronic document on web was unreadable)
  We impose a permutation symmetry S3 upon the two Higgs doublet extension of
the SU(2) x U( 1) standard model, and then break S3 symmetry spontaneously. A
mass relation is obtained from which the mass of the top quark is predicted to
be 39 Gev at 1 Gev renormalization scale, if the relative strength between the
coupling of the first Higgs field with the up-type quarks is assumed to be the
same as that with the down-type quarks. We find that in our model the flavor
changing neutral currents vanish automatically.
