  Let $(M,P\nabla_M)$ be a compact projective manifold and $Aut(M,P\nabla_M)$
its group of automorphisms. The purpose of this paper is to study the
topological properties of $(M,P\nabla_M)$ if $Aut(M,P\nabla_M))$ is not
discrete by applying the results that I have shown in [13] and the Benzekri's
functor which associates to a projective manifold a radiant affine manifold.
This enables us to show that the orbits of the connected component of
$Aut(M,P\nabla_M)$ are immersed projective submanifolds. We also classify
$3$-dimensional compact projective manifolds such that
$dim(Aut(M,P\nabla_M))\geq 2$.
