  We investigate the forward-backward asymmetries in the pair production of
fourth family fermions through the new Z' interactions in the e+e- collisions.
The Z' boson having family universal couplings can contribute to the pair
production of fourth family fermions via the s-channel exchange. The linear
colliders will provide a clean environment for the physics of Z' boson to
measure its couplings precisely. The effects of the Z' boson to the asymmetries
are shown to be important in some parameter regions for different Z' models.
Among these parameters, the invariant mass distribution m_FFbar will be an
important measurement to constrain the Z' models. Providing the fourth family
fermion exist in an accesssible mass range, a chi^2 analysis can also be used
to probe the Z' models at linear collider energies.
