  IIn this article, we study the instanton equation on the cylinder over a
closed manifold $X$ which admits non-zero smooth $3$-form $P$ and $4$-form $Q$.
Our results are (1) if $X$ is a \textbf{good} manifold, i.e., $P,Q$ satisfying
$d\ast_{X}P=d\ast_{X}Q=0$, then the instanton with integrable curvature decays
exponentially at the ends, and, (2) if $X$ is a real Killing spinor manifold,
i.e., $P,Q$ satisfying $dP=4Q$ and $d\ast_{X}Q=(n-3)\ast_{X}P$, we prove that
the solution of instanton equation is trivial under some mild conditions.
