  In this paper, we consider the following elliptic system \begin{equation*}
\begin{cases} -\Delta u = |v|^{p-1}v +\epsilon(\alpha u + \beta_1 v), &\hbox{
in }\Omega, \\-\Delta v = |u|^{q-1}u+\epsilon(\beta_2 u +\alpha v), &\hbox{ in
}\Omega, \\u=v=0,&\hbox{ on }\partial\Omega, \end{cases} \end{equation*} where
$\Omega$ is a smooth bounded domain in $\mathbb{R}^{N}$, $N\geq 3$, $\epsilon$
is a small parameter, $\alpha$, $ \beta_1$ and $ \beta_2$ are real numbers,
$(p,q)$ is a pair of positive numbers lying on the critical hyperbola
\begin{equation*} \begin{split} \frac{1}{p+1}+\frac{1}{q+1} =\frac{N-2}{N}.
\end{split} \end{equation*} We first revisited the blowing-up solutions
constructed in \cite{Kim-Pis} and then we proved its non-degeneracy. We believe
that the various new ideas and technique computations that we used in this
paper would be very useful to deal with other related problems involving
critical Halmitonian system and the construction of new solutions.
