  We study the tachyon scalar field model in flat FRW cosmology with the
particular potential $\phi^{-2}$ and the scale factor behavior $a(t)=t^n$. We
consider the spherical collapse model and investigate the effects of the
tachyon scalar field on the structure formation in flat FRW universe. We
calculate $\delta_{c}(z_{c})$, $\lambda(z_{c})$, $\xi(z_{c})$,
$\Delta_{V}(z_{c})$, $\log [\nu f(\nu)]$ and $\log [n(k)]$ for the tachyon
scalar field model and compare the results with the results of EdS model and
$\Lambda CDM$ model. It is shown that in the tachyon scalar field model the
structure formation may occur earlier, in comparison to the other models.
