  We have studied in this paper, the stability of dynamical system in $f(R)$
gravity. We have considered the $f(R)$ $\gamma$-gravity and explored its
dynamical analysis. We found six critical points among which only one describes
an universe fulled of both matter and dominated dark energy. It's shown that
these critical points presents specific phase spaces described by the
corresponding fluids. Furthermore, we've investigated the stability conditions
of these critical points and find that theses conditions are dependent of the
model parameters. We also study the stability of a new power-law $f_\ast(R)$
model with de Sitter and power law solutions.
