In this talk, we will discuss locally conformally flat manifolds with finite total curvature. We prove that for such a manifold, the integral of the $Q$-curvature equals an integral multiple of a dimensional constant. This shows a new aspect of the $Q$-curvature on noncompact complete manifolds. It provides further evidence that $Q$-curvature controls geometry as the Gaussian curvature does in two dimension on locally conformally flat manifolds.