  We have calculated the full one-loop electroweak (EW) and QCD corrections to
the third generation scalar-fermion pair production processes $e^+e^- \to
\gamma \gamma \to \tilde{f_i}\bar{\tilde{f_i}} (f=t,b,\tau)$ at an
electron-positron linear collider(LC) in the minimal supersymmetric standard
model (MSSM). We analyze the dependence of the radiative corrections on the
parameters such as the colliding energy $\sqrt{\hat s}$ and the SUSY
fundamental parameters $A_f$, $\tan \beta$, $\mu$, $M_{SUSY}$ and so forth. The
numerical results show that the EW corrections to the squark-, stau-pair
production processes and QCD corrections to the squark-pair production
processes give substantial contributions in some parameter space. The EW
relative corrections to squark-pair production processes can be comparable with
QCD corrections at high energies. Therefore, these EW and QCD corrections
cannot be neglected in precise measurement of sfermion pair productions via
$\gamma\gamma$ collision at future linear colliders.
